This easy brownie cake is for all of the brownie lovers out there! It has all of the wonderful flavor of brownies in the form of a two layer cake.
This cake is made from a doctored brownie mix, which is why it has the flavor and texture of a cake-like brownies. It has delicious chocolate brownie flavor without being overly rich.
At two layers, it doesn't stand quite as tall as our usual cakes (approximately an inch shorter), but is every bit as impressive!
Keep this brownie cake in mind the next time you need a great birthday cake recipe, potluck dessert, holiday cake, and more!
Table of Contents
Ingredients for Brownie Cake
Here is a quick look at the star players in today's easy brownie cake recipe:
Duncan Hines Double Fudge Brownie Mix- This has been our favorite brownie mix to use with this recipe so far, but we have only tested one other. (We discuss this more in the notes). It comes with a packet of fudge syrup which we used in the batter as well!
Flour and Sugar: These ingredients help to extend the recipe further, and also give the brownie layers a more "cake like" quality.
Baking Powder: We added a teaspoon of powder to the brownie batter to give it a bit more rise.
How to Make a Brownie Cake
- Grease two 8 inch cake layers. We also added circles of parchment to the bottom of each pan (as usual).
- This recipe can be prepared in a large mixing bowl, just as when making brownies. No electric mixer is needed.
- Combine dry ingredients in large bowl and whisk together. (This is the brownie mix, flour, sugar, cocoa powder, and baking powder.)
- Add the remaining ingredients (eggs, sour cream, fudge packet (if your mix has one), water, and vegetable oil) and stir until well combined. I prefer to use a rubber spatula for this step.
- This recipe makes 5 cups of batter, enough for two 8 inch cake layers. Divide the cake batter between two 8 inch round cake pans and place in the oven.
- Bake at 350 for 25-30 minutes, or until a toothpick can be inserted and comes out clean or with just a few crumbs attached.
Cool the layers on a wire rack for 5 minutes before turning out. Make sure to cool them completely before frosting.
Chocolate Buttercream Frosting
There are many frostings and fillings that would pair well with this chocolate brownie cake recipe!
Today, we opted for Chocolate Buttercream. This delicious recipe is so simple to make. It is a combination of softened butter, confectioners sugar, unsweetened cocoa powder, milk, vanilla extract, and a pinch of salt.
If the frosting is too thick, add a bit more milk. If it is too thin, add a bit more confectioners sugar.
Assembling the Brownie Cake
Once the brownie cake layers have completely cooled, place the first layer on a cake base or pedestal. Spread with a layer of chocolate frosting.
Top with the next brownie cake layer. Apply a thin layer of frosting on top and around the sides of the cake. (This is the crumb coat.)
At this point, we like to chill the cake for 15 minutes in the freezer to firm everything up (or longer in the refrigerator). Then, apply the second layer of chocolate frosting.
Decorating the Brownie Cake
Decorate however you like! I used a small offset spatula to add texture around the sides of the cake by creating simple diagonal strokes.
For the top of the cake, I added rows of buttercream shells and then piped a buttercream rosette in the center.
All of this was done with a large star (1M) piping tip. (Find more details in our video on the basics of star tip piping!)
Here is a peek at the inside of the cake!
More Chocolate Cakes
If you love chocolate cakes, we have so many to share with you!
- 1 Box Brownie Mix (We like Duncan Hines Double Fudge Brownie Mix- 17.6 oz) *See Notes
- ½ cup (60g) All Purpose Flour
- ½ cup (100g) granulated sugar
- 1 teaspoon (4g) Baking Powder
- 2½ Tablespoons (15g) Unsweetened Cocoa Powder
- ½ cup (108g) vegetable oil
- 1 cup sour cream (we use full fat)
- ½ cup water
- 3 large eggs
- Fudge Packet (if your brownie mix comes with one)
For the Chocolate Buttercream
- 2 sticks (226g) unsalted butter, softened (Do not microwave)
- 6 cups (690g) powdered sugar
- ¾ cup (70g) unsweetened cocoa (measure then sift)
- ⅓ -½ cup (72g) milk (adjust amount for desired consistency)
- 2 teaspoons 8g vanilla extract 8 grams
- ½ teaspoon 3g salt
- Preheat oven to 350℉. Grease two 8 inch round cake pans. We also added circles of parchment to the bottom of each pan (as usual).
- This recipe can be prepared in a large mixing bowl, just as when making brownies from a mix. No mixer needed.
- Combine dry ingredients in large bowl and whisk together until combined. (This is the brownie mix, flour, sugar, cocoa powder, and baking powder.)
- Add the remaining ingredients (eggs, sour cream, fudge packet (if your mix has one), water, and vegetable oil) and stir until well combined. I find it easiest to use a rubber spatula for this step.
- Divide the cake batter between two 8 inch cake pans. (This recipe makes about 5 cups of batter.)
- Bake at 350℉ for 25-30 minutes or until a toothpick can be inserted into the cake layers and comes out clean or with just a few crumbs attached.
- Cool the cake layers in the cake pans (preferably on a cooling rack) for 5 minutes before turning out. Cool completely before frosting.
For the Chocolate Buttercream
- Add butter and mix on low to medium speed until smooth. Add vanilla and blend into the butter.
- Add powdered sugar, salt, and cocoa powder.
- Add most of the milk and mix on low speed, increasing to medium as the ingredients become incorporated.
- Continue to mix adding remaining milk as needed. It may take 3-5 minutes to reach the smoothness and consistency you like. It will take longer if using a hand mixer. As you mix, the frosting will become very smooth. You can add additional milk (1 Tablespoon at a time) if the frosting is too thick or additional powdered sugar if too soft.
Decorating the Cake
- Place the first cake layer on a cake pedestal and spread with frosting. Top with the second cake layer and frost the cake around the sides and top with a thin layer of frosting. (This is the "crumb coat".)
- At this point, we like to chill the cake in the freezer for 15 minutes (or longer in the refrigerator) to firm everything up. (Chill the bowl of frosting in the refrigerator during this time if needed).
- Frost the cake with a second layer of frosting. Decorate however you like! At this point, we added texture around the sides of the cake using a small offset spatula, making diagonal strokes from bottom to top.
- We added additional piping on top of the cake, piping large frosting shells using a large star (1M) piping tip.
- Keep the cake in an airtight container or under a cake dome in a cool room in your house for 1-2 days or in refrigerator for longer. If refrigerating, you should remove the cake a couple of hours before serving so that it has time to warm and soften.