One Pan Double Chocolate Cake with Fluffy Chocolate Buttercream

When you have a BIG craving for dark chocolate and cake but a small (2-person) household like ours, the only solution is my One Pan Double Chocolate Cake Recipe, topped with a fluffy chocolate buttercream frosting. This quick and easy single-layer cake is flavored with both cocoa and melted chocolate, making it perfect for all my fellow chocoholics!

⭐ Why You’ll Love This Recipe 

One-pan cake recipes have become a favorite of Calvin and mine, especially since we haven’t been as social for the past couple of years in the midst of a pandemic. As much as I love professionally baking (and enjoying!) layer cakes, we don't always have the space for them on the regular!

This single-layer double chocolate cake recipe brings all the flavor of a mile-high fudge cake, but without all the extra fuss. In fact, I’d go so far as to say that this could be considered an “everyday” cake because it is so easy to pull off.

My friends, I feel the need to clarify that just because this is an easy chocolate cake recipe DOES NOT mean it is anything less than stunning. The dark chocolate cake itself is oozing with truffle vibes, offering deep chocolate flavor and a moist, tender crumb. The dark chocolate buttercream frosting is cloudlike in its consistency. And the two together? Well, they’re a match made in heaven.

However, if you’re one of those people who aren’t quite on board with the theme of doubling down on the dark chocolate, no worries! That fluffy dark chocolate buttercream frosting can easily be made into a milk chocolate or white chocolate affair instead. Or, go rogue and try this sumptuous raspberry buttercream recipe instead. There’s something here for everyone!

So go ahead and give yourself permission to make this celebratory chocolate cake just because. You’re worth it! And, if I’m being entirely honest, any day that ends with cake is a pretty sweet day indeed.

🍴Ingredients

This simple dark chocolate cake recipe has a relatively short ingredient list, and I’d bet most of the items are already in your pantry. That said, I have a few notes for you:

• Cocoa Powder - I prefer using Dutch-process cocoa powder, which has lower acidity and less bitterness than natural cocoa powder. Curious about different types of cocoa powder? Feel free to nerd out with this interesting article!
• Dark Chocolate - For the actual cake recipe, I suggest using either dark or semisweet chocolate for the best results, but feel free to get creative with the buttercream frosting! I love doubling up on my dark chocolate, but the frosting recipe will work just as well with milk or white chocolate. If you’re feeling even more adventurous, I suggest checking out Valrhona’s Inspiration chocolate line - it’s out of this WORLD.
• Espresso - If you’ve never tried adding espresso (or strong coffee) to your chocolate bakes, you’re in for a real treat. Adding coffee to chocolate-based desserts makes the chocolate taste even more chocolatey! If you’re concerned about adding too much caffeine, feel free to opt for decaf. And if you’re not a coffee drinker, try keeping a jar of instant espresso in the baking aisle in your pantry.

• Sprinkles - This dark chocolate cake is a delight even if you just top it with my fluffy chocolate buttercream frosting, but it’ll instantly feel more celebratory with the addition of some fun sprinkles.

⚒️ Equipment

• Hand or Stand Mixer - While you can easily get away with making the cake batter by hand, I strongly recommend you invest in an electric mixer to help you get the lightest, fluffiest buttercream frosting possible.
• 8-inch Cake Pan - The beauty of this dark chocolate cake recipe is that you only need one pan. If you have a different-sized cake pan, refer to this awesome cake pan conversion chart to help you out. You can also skip to the “Optional Variations” section below for information on how to turn this recipe into cupcakes or a mini 6” layer cake!
• Parchment Paper - Even if you use non-stick pans and grease them, there can still be cakes that tear on their way out of the tin. Do yourself a favor and use parchment rounds to ensure a beautiful and professional result every single time! And if you’re worried about the environmental impact, don’t fret - parchment can be composted after use. 
• Cooling Rack - Cooling racks are excellent for helping get your cake frosted and into your mouth quicker. If you don’t want to add another piece of equipment to your arsenal, try using the insert from your toaster oven or your baking pan rack insert instead.

📖 Step by Step Instructions

This single-layer double chocolate cake will be ready for eating before you know it. Here’s how it’s done:

Make Cake Batter

Preheat your oven to 350 degrees Fahrenheit. Whisk together the flour, brown sugar, cocoa powder, baking soda, baking powder, and salt in a mixing bowl. 

In a separate bowl whisk together the buttermilk, oil and egg until smooth. Pour the wet ingredients into the dry and mix until fully incorporated. 

Want to make your own buttermilk from scratch? Check out my guide for making homemade buttermilk or vegan buttermilk!

Add the melted dark chocolate and coffee - then mix to combine.

Bake & Cool

Pour batter into a greased 8-inch cake pan and bake for 30-35 minutes. Make sure to check that the cake is fully baked with a toothpick before removing it from the oven. Allow it to cool for about 5-10 minutes in the pan before inverting onto a cooling rack and allowing it to cool completely. 

Make Chocolate Frosting

In a mixing bowl, beat the butter on medium speed until smooth.

Add approximately half of the powdered sugar and beat again. Scrape the sides of the bowl and add the rest of the powdered sugar. Continue beating for about a minute, scraping the sides as needed, until the mixture is smooth and creamy.

Finally, add the vanilla paste and chocolate and continue beating until the frosting is thick and fluffy. 

Assemble and Enjoy!

Dollop the chocolate buttercream onto your fully cooled chocolate cake. Using the back of a spoon or an offset spatula, push the frosting into pretty swirls across the top of the cake. Decorate with sprinkles, cacao nibs, dark chocolate shavings, and/or the toppings of your choice, then dig in and enjoy!

Looking to create delicious and homemade garnishes to elevate your creations? Try adding Sugared Flowers, Candied Rose Petals, Dried Orange Slices or Sugared berries!

⏲️ Substitutions & Variations

• Different sizes make the world go round! This is an incredibly versatile recipe - instead of using a single 8-inch cake pan, you could turn this chocolate cake into two 6-inch cakes or cupcakes! Due to the different vessel sizes, you’ll need to adjust the times depending on the type of pan that you use. Here are some tested bake times and pan sizes:

• 2 6-inch cake pans: Bake for 35-40 minutes
• Cupcake Tins: Bake for 25-30 minutes

Swap dark chocolate buttercream for a different type of chocolate (or different flavor altogether!). White, milk, semisweet, or even flavored chocolate will work in the buttercream frosting recipe. You can also play with different, non-chocolate flavors if you like. Try my berry buttercream, almond buttercream, salted caramel buttercream, or any other frosting that makes intrigues you!

👩🏻‍🍳 Expert Tips

• Remember to preheat your oven before making your batter. Both baking soda and baking powder begin to react as soon as they touch liquid. If you wait too long before putting the cake in the oven, you’ll lose out on some of their lifting powers, resulting in a denser, chewier cake.
• Layering on the garnish. Just because the cake itself isn’t layered doesn’t mean your decorations can’t be. I added a couple of different layers of toppings, starting with some finely chopped dark chocolate sprinkled around the edge. Then I added some cacao nibs, crispearls, and sprinkles to finish.
• Don’t diss the microwave. While I’m all for using a double boiler when there is a lot of chocolate to be melted, there’s exactly zero shame in using the microwave for smaller amounts as are needed here. This is a SIMPLE recipe, after all! To microwave chocolate, use a heat-proof bowl and zap in 10 second increments, stirring between each, until the chocolate is 90% melted. Keep stirring after it is mostly melted - the chunks should eventually succumb to the heat of their surroundings.

💭 Recipe FAQs

More Smaller Size Cake Recipes

If you try the recipe for this One Pan Double Chocolate Cake, please leave a 🌟 review and share your creation with me on social media! You can find me on Instagram, Facebook, Youtube and Pinterest - for more delicious recipes sent straight to your inbox, sign up for my newsletter! 📧