Moist 6-inch Chocolate Cake (single layer)
This 6-inch chocolate cake recipe is for a moist single-layer chocolate cake. It is frosted with a smooth chocolate Swiss meringue buttercream frosting.
A small 6-inch chocolate cake like this serves 6-8 slices making it perfect for a small group of people. It has a fluffy chocolate cake base, paired with a luscious and smooth chocolate Swiss meringue buttercream frosting. See more small-batch recipes!
The frosting
Chocolate buttercream is always great but this version uses a Swiss meringue method which makes the frosting smooth, shiny, and most importantly gives a delicious chocolate flavor. It’s much less sweet than American buttercream too and pairs perfectly with the cake.
To make Swiss meringue buttercream, heat egg whites with granulated sugar, and salt until all the sugar has dissolved. Whip the egg whites using a stand mixer until stiff glossy peaks are formed. When the meringue is cooled, add the butter in slowly while continuing to mix. You can use the leftover yolks in these egg yolk cookies.
After the butter has all been incorporated, add the melted chocolate. The end result is a creamy frosting that is extra smooth and not overly sweet.
The ingredients
The ingredient amounts for this cake are listed in the recipe card at the bottom of this post. Here is just a rundown of some of what is used with a little extra information.
- Unsweetened cocoa powder – Cocoa powder gives the cake a chocolate flavor and is a key ingredient in the cake mix. You can use natural cocoa powder or dutch-processed cocoa powder but natural will give the deepest flavor.
- Granulated sugar and brown sugar.- The brown sugar sweetens the cake alongside the granulated white sugar and it brings some moisture.
- Oil – The oil helps make the cake batter rich and smooth and keeps things moist. I like to use melted coconut oil but you can use vegetable oil too.
- Apple cider vinegar (ACV) or white vinegar- A little vinegar brings some acidity to make a tender cake.
- Egg – One large egg to give some structure.
- Hot coffee or hot water – Hot water is added to some instant coffee or espresso powder. Coffee deepens the chocolate flavor a lot. If you want to omit it, substitute it with plain hot water.
Method
- Preheat the oven to 350°F/ 180°C. Grease and line a 6-inch cake pan.
- Whisk the dry ingredients.
- In a separate bowl add the egg, sugars, vanilla, and vegetable oil and whisk together
- Mix in the dry ingredients alternating with milk and vinegar
- Pour in the hot coffee and fold it in until everything is well combined, but don’t over-mix it.
- Bake and let the cake cool before frosting.
- Decorate how you like!
Serving and storing
Leftover cake can be stored at room temperature in an airtight container for up to 3 days or in the fridge for up to 5 days.
The unfrosted baked cake can also be frozen for up to three months.
Swiss meringue buttercream can be made in advance at can be stored at room temperature for up to 3 days or in the fridge for up to 5 days. It can also be frozen for up to three months. Refrigerated or frozen Swiss meringue buttercream will need to come to room temperature and re-whipped again to make it fluffy.
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Moist 6-inch Chocolate Cake (Single layer)
Ingredients
- 83 g all-purpose flour
- 25 g cocoa powder natural or dutch processed
- 1/2 teaspoon baking powder
- 1/4 teaspoon baking soda
- 1/4 teaspoon salt
- 1 large egg
- 66 g granulated sugar
- 50 g soft brown sugar
- 45 g oil vegetable or melted coconut oil
- 1/2 teaspoon vanilla paste or extract
- 1/2 teaspoon Apple cider vinegar or white vinegar or lemon juice
- 60 g whole milk
- 60 g hot coffee or use hot water
Chocolate Swiss meringue buttercream
- 2 large egg whites 60g/2 oz
- 66 g granulated sugar
- Pinch salt
- 170 g unsalted butter softened to room temperature.
- 113 g semi-sweet chocolate
- 1/2 teaspoon vanilla paste or extract
Instructions
- Preheat the oven to 350°F/ 180°C. Grease and line a 6×3-inch round cake pan.
- In a bowl whisk together the flour, cocoa powder, baking powder, baking soda, salt, and set aside.
- Measure out the milk and add the vinegar or lemon juice. Let this sit and curdle for a couple of minutes.
- In a separate bowl add the egg, sugars, vanilla, and vegetable oil and whisk together.
- Add ⅓ of the dry ingredients at a time to the egg mixture in the bowl along with ⅓ of the milk and fold it together with a rubber spatula. Repeat this with the remaining flour and milk.
- Pour the hot coffee into the batter and fold it until well combined.
- Pour the cake batter into the prepared ban and bake for approximately 30-35 minutes until a cake tester inserted into the middle of the cake comes out clean. The bake time will change depending on your oven.
Frosting
- Melt the chocolate in a bowl in the microwave and set it aside to let it cool to room temperature.
- In the metal bowl of your stand mixer, or other heatproof bowl, add egg whites, sugar, and salt. Bring a pot with 1-inch of water to a simmer and balance the bowl over top but not touching the water.
- Whisk constantly until the mixture becomes foamy and all the sugar has dissolved when a little is rubbed between your fingers. If you have a thermometer, the temperature should be around 160F/71C.
- Place your bowl in your stand mixer fitted with a whisk attachment and begin whisking the meringue on medium speed until the meringue has cooled down completely to room temperature and it's thick and glossy with stiff peaks. Touch the sides of the bowl to check. It should be cool to the touch.
- Begin adding in the butter, a cube at a time, and not adding in the next cube until the previous cube has been completely incorporated. Once the butter is incorporated the mixture can split and look curdled and grainy. This is normal.
- Switch the mixer to high speed and keep beating until the mixture comes together and is smooth and thick. See the notes for troubleshooting.
- Turn off the mixer and pour in the melted chocolate and vanilla. Turn the mixer high and keep beating until the chocolate is all incorporated and the frosting is fluffy.
- Switch to the paddle attachment and beat on low speed for 5-10 minutes to remove some of the larger air bubbles in the buttercream.
- Scoop the chocolate swiss meringue buttercream on top of the cooled cake. Use an offset spatula to generously spread it around to coat the top of the cake and the sides. Store leftover cake in an airtight container at room temperature for up to three days.
Notes
Buttercream notes
If the meringue is too warm before adding butter:- The butter will melt, resulting in a soupy or runny texture.
- Solution: Chill the bowl briefly, then re-whip until smooth.
- The buttercream will appear curdled or lumpy.
- Solution: Gently warm the mixture by placing the bowl over warm water for a few seconds, then re-whip.
I have been using this recipe for 30 times and it has not failed me once! Thanks for making such a great recipe.
So happy you love the recipe Chad!