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Lemon poppyseed berry buttercream cake.
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5 from 7 votes

3-Layer Poppyseed Lemon Cake with Blackberry Buttercream

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!
Prep Time1 hour
Cook Time30 minutes
Total Time1 hour 30 minutes
Course: Dessert
Cuisine: American
Servings: 10 Slices
Calories: 873kcal
Author: Emily Laurae

Ingredients

Lemon Poppyseed Cake

  • 3 Cups All-Purpose Flour
  • 1 tablespoon Baking Powder
  • 2 tablespoon Poppyseeds
  • 4 Lemons zested
  • ¾ tsp Salt
  • 4 Large Eggs room temperature
  • 1 ¾ Cup Granulated Sugar
  • 1 Cup Neutral Oil Avocado, Canola, Grapeseed
  • 2 tsp Lemon Extract
  • 1 Cup Buttermilk

Berry Buttercream

  • 3 Egg Whites
  • 1 Cup Granulated Sugar
  • 1 ⅓ Cup Unsalted Butter Room Temperature
  • ½ Cup Berries frozen or muddled - pick the berries of your choosing!

Lemon Blackberry Simple Syrup

  • ½ Cup Water
  • ½ Cup 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

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.
  • 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:
    1. 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.
    2. 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.
    3. 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.

Nutrition

Calories: 873kcal | Carbohydrates: 102g | Protein: 9g | Fat: 50g | Saturated Fat: 19g | Polyunsaturated Fat: 17g | Monounsaturated Fat: 11g | Trans Fat: 1g | Cholesterol: 133mg | Sodium: 374mg | Potassium: 214mg | Fiber: 3g | Sugar: 68g | Vitamin A: 909IU | Vitamin C: 29mg | Calcium: 163mg | Iron: 3mg
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