Good things come in small packages, and this 3-Layer Poppyseed Lemon Cake with Blackberry Buttercream is proof. While it is a mere 6 inches in diameter, this moist and flavorful celebration cake is a gorgeous, towering, and tasty dessert that you won’t soon forget!

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⭐ Why You’ll Love This Recipe
Spring is in the air, and I have a hankering for bright flavors and pretty pastel hues! With 3 layers of sweet, tart, crunchy, and delectably moist cake and a sumptuous raspberry-blackberry buttercream frosting, this beautiful Poppyseed Lemon Cake delivers on all fronts!
Lemon poppyseed is a classic pairing that I can’t seem to get enough of. Bright, sunshiny lemon meets crunchy poppyseeds for a taste and textural explosion that is delicious. Honestly, whoever came up with the combination is a true hero.
Add a berry-flavored Swiss meringue (that also happens to be naturally colored from the berries) and a blackberry simple syrup into the mix, and you have a cake that I just can’t stop talking about!
While a 3-layer cake might seem like a daunting undertaking, I’m here to assure you that it is entirely within your grasp. I use 3 separate 6-inch round cake pans to bake the layers, and weigh the batter to ensure even layers.
The cakes are then brushed with a berry-flavored simple syrup to double down on the berry flavor and provide an additional punch of moisture to the tender crumbed cake. Finally, each layer is generously frosted with a pale pastel Swiss buttercream flecked with bits of berries before being stacked into this marvelous centerpiece.
Best of all, my poppyseed lemon cake can be completed in under two hours! My friends, this is a weekend baking project I promise you can handle. You can also split it up into smaller tasks over the course of a couple of days in case you need a real show-stopper for your mid-week dinner party.

🍴Ingredients
One of the things I love most about this poppyseed lemon cake is how humble the ingredients are. I have a feeling you already have a lot of them on hand! Here are a few notes to keep in mind:
For the Lemon Poppyseed Cake:
- Baking Powder - This is a different ingredient than baking soda, and the two should not be used interchangeably. Also, make sure your leavening is relatively fresh; it can lose reactive power over time.
- Lemons - Definitely reach for fresh here. Not only is the juice far superior to the bottled kind, but you’ll also want the added zing of the zest.
- Neutral Oil - Vegetable, canola, corn, peanut, avocado, or grapeseed oil will all work here.
- Lemon Extract - The bright lemon extract helps to intensify the lemon flavor of this cake. Feel free to use equal amounts of either vanilla paste or vanilla extract if you prefer.
- Buttermilk - Buttermilk is a real essential in a baker’s kitchen. If you don’t have any on hand, make your own by adding about a teaspoon of lemon juice or white vinegar to each cup of milk (either dairy or plant-based) and stir. Let it sit for a few minutes to thicken and curdle before using. Want to make your own buttermilk from scratch? Check out my guide for making homemade buttermilk or vegan buttermilk!
For the Berry Buttercream:
- Egg Whites - Remember that eggs are easiest to separate when they are cold from the fridge, but you should let them come to room temperature before incorporating them into your recipes.
- Granulated Sugar - You need plain white table sugar for all three stages of this recipe, so make sure you’re stocked.
- Unsalted Butter - Opt for organic, grass-fed, and/or cultured butter whenever possible. Non-dairy will work as well.
- Blackberries - Honestly, any kind of berry will work here, so feel free to go wild. You can use fresh or frozen, and feel free to mix and match to your heart’s content!

⚒️ Equipment
Building up an arsenal of baking equipment can take some time, but I promise it is well worth the money and effort. Here are some of my tool suggestions for this poppyseed lemon cake with blackberry buttercream:
- 3 6-inch Cake Pans - Having smaller cake pans on hand is wonderful if you live in a small household like mine. They’re also excellent for creating lofty yet still manageable-sized cakes like this one. If needed, you can use two 8-inch cake pans instead, but note that you may need to cut back the bake time a bit to prevent burning.
- Parchment Paper - Even if you grease your pans perfectly, there’s still a chance that a stubborn crumb will stick to the bottom of your pan and tear your cake. Ensure your cakes release perfectly every time by using rounds of parchment paper to line your tins.
- Offset Spatula- If you’re new to the cake decorating game, offset spatulas are a real game-changer. You’ll be able to get perfectly iced sides with far less effort.
- Cake Turntable/Lazy Susan - Again, this is a cake decorating essential. Feel free to use a regular lazy susan if you don’t have a dedicated cake table. The ability to spin the cake while you’re frosting makes it far easier to get an even layer.
📖 Step by Step Instructions
This recipe for my poppyseed lemon cake can be broken into four steps, each of which can be completed in advance.
Please note that the cake layers can be baked, cooled, wrapped well in plastic, and either refrigerated for up to 2-3 days or frozen for up to a month!
The blackberry buttercream will last for 2-3 days if covered in the fridge; just make sure to let it come to room temperature and give it a good whip before frosting. The blackberry simple syrup can be made up to 10 days in advance.
STEP 1: Make Poppyseed Lemon Cake
Prep: Preheat your oven to 350 degrees Fahrenheit. Grease and line 3 6-inch round cake tins with parchment.
Dry ingredients: Sift together the dry ingredients – then add in your poppyseeds and lemon zest.
Wet ingredients: Separately, using a standing mixer or a whisk, combine the eggs, sugar, oil, and vanilla extract with the paddle attachment until combined.


Combine wet & dry: Alternate adding your buttermilk, and dry ingredients into the bowl of wet ingredients while mixing.


Bake: Divide your batter into 3 prepared 6-inch cake pans and bake for 25 minutes, or until your cakes pass the toothpick test and allow them to cool completely. Once cooled, slice off the slightly domed top of each cake to ensure that they are flat. Then carefully slice each 6-inch cake in half lengthwise so that you end up with six even layers.


Step 2: Make Blackberry Buttercream
Temper eggs & sugar: Add your sugar and egg whites to the bowl of a stand mixer and place over a saucepan of boiling water. Make sure that your bowl is not touching the hot water! Your goal here is to simply whisk the egg whites and sugar together over a gentle heat until the sugar has completely dissolved, then attach your bowl back to the standing mixer. The temperature should read 165 F before it’s ready to be removed from the heat.
Whip: Whisk mixture starting at a low speed and gradually increase until soft peaks form and the mixture has cooled. Switch to using your paddle attachment, then start adding your butter bit by bit.
Add berries: When you’ve reached the point where the buttercream is glossy and smooth, turn the mixer speed back to low. Add berries, and mix on low until combined.

Step 3: Make Lemon & Blackberry Simple Syrup
Make simple syrup: Pour your measured water and sugar into a saucepan place over medium heat. Cook, stirring the mixture until your sugar has completely dissolved.
Steep: Add lemons & blackberries and continue heating for 30 seconds before removing the pan from heat. Allow syrup to infuse for half an hour as the simple syrup cools completely then strain the syrup into an airtight container and store in the fridge until ready to use!

Step 4: Assemble Your Layer Cake
Add moisture: Brush or pour the blackberry simple syrup on the top of your first cake layer.
Add frosting: Spread the first layer of buttercream on top. Place the second cake layer on top of the first and repeat the above process adding simple syrup and buttercream.

Stack layers and frost outside: Repeat these two processes for all 3 layers of cake. Frost the edges of the cake with your remaining buttercream and place your cake in the fridge until ready to enjoy!
Garnish: If you’d like a little extra wow to this stunning berry buttercream poppyseed lemon cake, I find that piling on some fresh berries and a bit of edible greenery really does the trick!
Looking to create delicious and homemade garnishes to elevate your creations? Try adding Sugared Flowers, Candied Rose Petals, Dried Orange Slices or Sugared berries!
🍰 Simple Syrup to Ensure Moist Cake
At its core, simple syrup is the process of dissolving sugar into an equal amount of water. That’s it! Simple syrup, as an ingredient, can be utilized in an infinite amount of ways within the culinary world. With the addition of another ingredient to these two base ingredients, you’ve created an infusion – all of a sudden you’ve taken a syrup that seems “simple” and kicked it up a notch!
Many bakers brush or pour simple syrup onto the tops of their layer cakes before adding buttercream in order to retain moisture and add flavor. This is an especially important tip if you are not planning on eating the entire cake in one day! The simple syrup will preserve the cake from drying out, and can also add additional flavor to your creation.
For this recipe, I made a blackberry simple syrup - yet the world is your oyster! Head on over to my post on Simple Syrup Infusions if you want to learn more about how to use your leftovers or various flavor options you can create.

🔪 Creating Flat Cake Layers
One of the biggest challenges of making a layer cake is ensuring the layers are flat (read: structurally sound). If the layers are wonky, you run the risk of gravity ruining your masterpiece. Here are three different ways to achieve smooth, sturdy building surfaces:
- Trim it. One option is to trim off the domed top of the cake with a serrated knife. By gently moving the knife back and forth until the cake dome is removed, you are left with a flat top.
- Buy a cake leveler. Another option is to purchase a cake leveler tool that will help you do essentially the same thing with some guided assistance.
- Try using cake strips. These strips of cloth are soaked with water and wrapped around cake pans while baking to prevent the edges of the cake from baking too quickly which can cause the cake can dome, crack or rise too quickly before potentially collapsing. You can purchase cake strips, or make your own.
👩🏻🍳 Expert Tips
If you’re feeling a little intimidated at the thought of making a 3-layer cake, I totally understand. But, you won’t know that you can do it until you just do! Here are a few of my best tips for ensuring that this poppyseed lemon cake with blackberry buttercream turns out to be the stunner of your dreams:
- Don’t zest too far. Citrus zest has a concentrated amount of naturally occurring essential oils, which can add a ton of flavor to your cooking. However, the zest that you want is just the top layer where you can still see color. Avoid the white pith, as it is quite bitter. A microplane zester comes in quite handy for this.
- Be judicious with your berries. When adding the berries to your buttercream, make sure to move slowly; if you add too much liquid or too many berries, the buttercream will not retain its silky smooth texture. Instead, it will break, leaving you with separated streaks of buttercream and juice. Nobody wants that!
- The scale is your friend. I find that the best way to ensure even layers is to weigh the cake batter evenly in each cake pan. For example, if you have mixed a total of 900 grams of cake batter, divide 300 grams of cake batter into three different pans to assure that you have even layers. NOTE: Take a measurement of your empty mixing bowl prior to starting the batter, then subtract that amount from the total when you weigh the batter.

💭 Recipe FAQs
To ensure even slices, I find that marking the top of the cake lightly with the knife acts as a great guide. First, mark the median. Rotate the cake 90 degrees and mark that median. Next, lightly mark each quarter into halves or thirds.
After the first slice is out, things get a little easier. Feel free to use a piece of parchment paper so you can use your non-dominant hand as a guide in tandem with your dominant hand and the board edge of your knife.
I also suggest that you wipe the knife between cuts to ensure a clean-looking slice.
If you are not serving the entire cake all at once, use a piece of parchment paper to keep the cake from drying out!
Turns out, that Seinfeld episode was not a lie! Poppyseeds can in fact show up on a drug test for 2-3 days after ingesting them.
Certainly! You can use frozen blackberries as a substitute, just ensure they are thawed and drained properly. If you're looking for a different flavor altogether, raspberry or blueberry can be a great alternative in the buttercream. Add edible flowers to the side of the cake for the ultimate presentation!
Absolutely! The tangy and sweet flavor profile of a lemon poppy seed fluffy cake pairs wonderfully with a scoop of vanilla ice cream, homemade lemon curd or even a lemon sorbet for an extra citrusy touch.
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3-Layer Poppyseed Lemon Cake with Blackberry Buttercream
Equipment
Ingredients
Lemon Poppyseed Cake
- 3 Cups (375 g) All-Purpose Flour
- 1 tablespoon Baking Powder
- 2 tablespoon Poppyseeds
- 4 Lemons, zested
- ¾ tsp Salt
- 4 Large Eggs , room temperature
- 1 ¾ Cup (350 g) Granulated Sugar
- 1 Cup (224 g) Neutral Oil, Avocado, Canola, Grapeseed
- 2 tsp Lemon Extract
- 1 Cup (250 g) Buttermilk
Berry Buttercream
Lemon Blackberry Simple Syrup
- ½ Cup (120 g) Water
- ½ Cup (100 g) Granulated Sugar
- 5 Blackberries , lightly crushed/muddled
- 1 Lemon, Sliced in thin rounds
Instructions
Lemon Poppyseed Cake
- Preheat your oven to 350° Fahrenheit.
- Sift the dry ingredients into a medium bowl – your flour, baking powder, and salt. Finally, add lemon zest and poppyseeds on top of the sifted dry ingredients.3 Cups All-Purpose Flour, 1 tablespoon Baking Powder, 4 Lemons, 2 tablespoon Poppyseeds, ¾ teaspoon Salt
- Separately, using a standing mixer or whisk, combine the eggs, sugar, oil, and lemon extract with the paddle attachment until combined.4 Large Eggs, 1 ¾ Cup Granulated Sugar, 1 Cup Neutral Oil, 2 teaspoon Lemon Extract
- Alternate adding your buttermilk, and dry ingredients into the bowl of wet ingredients while mixing.1 Cup Buttermilk
- Divide your batter into 3 prepared 6-inch cake pans and bake for 35-38 minutes, or until a skewer/toothpick inserted into the cake comes out mostly clean with little to no crumbs attached. Then, allow them to cool completely. Once cooled, slice off the slightly domed top of each cake to ensure that they are flat.
Berry Buttercream
- Add your sugar and egg whites to the bowl of a stand mixer and place over a saucepan of boiling water.3 Egg Whites, 1 Cup Granulated Sugar
- Make sure that your bowl is not touching the hot water! Your goal is to simply whisk the egg whites and sugar together over a gentle heat until the sugar has completely dissolved, then attach your bowl back to the standing mixer. The temperature should read 165°F before it’s ready to be removed from the heat.
- Whisk mixture starting at a medium speed and gradually increase until soft peaks form and the mixture has cooled. Switch to using your paddle attachment, then start adding your butter one tablespoon at a time.1 ⅓ Cup Unsalted Butter
- When you’ve reached the point where the buttercream is glossy and smooth, turn the mixer speed back to low. Add berries, and mix on low until combined.½ Cup Berries
Blackberry Simple Syrup
- Pour your measured water and sugar into a saucepan and heat on medium. Cook, stirring the mixture until your sugar has completely dissolved.½ Cup Water, ½ Cup Granulated Sugar
- Add blackberries and lemon slices continuing to heat for 30 seconds before removing them from heat. Allow syrup to infuse for half an hour as the simple syrup cools completely then strain the syrup into an airtight container and store in the fridge until ready to use!5 Blackberries, 1 Lemon
Assembly
- Brush or pour the blackberry simple syrup on the top of your first cake layer.
- Spread the first layer of buttercream on top. Place the second cake layer on top of the first and repeat the above process adding simple syrup and buttercream.
- Repeat this process for the final layer of cake. Frost the edges of the cake with your remaining buttercream and place your cake in the fridge until ready to enjoy!
Notes
- Don’t zest too far. Citrus zest has a concentrated amount of naturally occurring essential oils, which can add a ton of flavor to your cooking. However, the zest that you want is just the top layer where you can still see color. Avoid the white pith, as it is quite bitter. A microplane zester comes in quite handy for this.
- Be judicious with your berries. When adding the berries to your buttercream, make sure to move slowly; if you add too much liquid or too many berries, the buttercream will not retain its silky smooth texture. Instead, it will break, leaving you with separated streaks of buttercream and juice. Nobody wants that!
- The scale is your friend. I find that the best way to ensure even layers is to weigh the cake batter evenly in each cake pan. For example, if you have mixed a total of 900 grams of cake batter, divide 300 grams of cake batter into three different pans to assure that you have even layers. NOTE: Take a measurement of your empty mixing bowl prior to starting the batter, then subtract that amount from the total when you weigh the batter.
- Make flat layers - a choose your own adventure tale. One of the biggest challenges of making a layer cake is ensuring the layers are flat (read: structurally sound). If the layers are wonky, you run the risk of gravity ruining your masterpiece. Here are three different ways to achieve smooth, sturdy building surfaces:
-
- Trim it. One option is to trim off the domed top of the cake with a serrated knife. By gently moving the knife back and forth until the cake dome is removed, you are left with a flat top.
- Buy a cake leveler. Another option is to purchase a cake leveler tool that will help you do essentially the same thing with some guided assistance.
- Use cake strips. These strips of cloth are soaked with water and wrapped around cake pans while baking to prevent the edges of the cake from baking too quickly which can cause the cake can dome, crack or rise too quickly before potentially collapsing. You can purchase cake strips, or make your own.
Lizzie
Hi, I made this and it turned out so cute and tasty-- but wondering if the amount of butter in the frosting is correct? It was a little heavy. Delicious otherwise! I really appreciate all of your tips for a great reasult.
Emily Laurae
So glad you enjoyed! Yes, the buttercream ratio is correct 😊