Egg White Chocolate Cake
This egg white chocolate cake is super fudgy, moist and rich. It’s a perfect dessert with leftover egg whites – both in the cake and the chocolate Swiss meringue buttercream frosting.
It’s a truely delicious chocolate cake – even if I wasn’t looking for ways to use egg whites I would make it! There’s sour cream in the batter to bring the extra fat to counter balance the missing egg yolks, and it makes it so moist. I add a tiny bit of vinegar to bring a bit of extra acidity, and creates a light and fluffy cake, as well as staying moist. At the end of mixing the batter I add in hot coffee. This helps to bloom the cocoa and bring out the flavour a bit and the coffee deepens the chocolate. You can just use hot water if you don’t want to use coffee.
The cake is a two layer 8-inch cake, and I sandwich it together with creamy chocolate Swiss meringue buttercream. It tastes like chocolate mousse and it’s so velvety smooth – it spreads like a dream!
Method
Here are some photos of the method step-by-step. Scroll down to the bottom of the post to find the printable recipe!
- Preheat the oven and grease and line 2 x 8-inch cake pans with parchment paper.
- Whisk together the dry ingredients to make sure there are no lumps
- In another bowl, whisk the wet ingredients except for the coffee or hot water.
- Mix in half the dry ingredients, then add the rest along with hot coffee.
- Whisk into a batter until combined, but don’t over-mix it.
- Pour into the prepared pans and bake.
- Let the cooled cakes cool completely to room temperature.
- Frost the cakes once they are cooled.
- Then it’s time to serve!
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Egg White Chocolate Cake
Ingredients
Cake
- 190 g all-purpose flour
- 50 g natural cocoa powder
- 1 1/2 teaspoon baking soda
- 1/2 teaspoon baking powder
- 3/4 teaspoon salt
- 3 large egg whites
- 150 g granulated sugar
- 100 g soft brown sugar
- 120 g sour cream room temperature
- 120 g whole milk room temperature
- 55 g oil (vegetable or melted coconut oil)
- 1 teaspoon apple cider vinegar or white vinegar or lemon juice
- 1 teaspoon vanilla paste or extract
- 180 g hot coffee or use hot water
Chocolate Swiss Meringue Buttercream
- 4 large egg whites
- 150 g granulated sugar
- 340 g unsalted butter softened to room temperature
- 230 g semi-sweet chocolate
- 1 teaspoon vanilla paste
- 1/4 teaspoon salt
Instructions
- Preheat the oven to 350°F/ 180°C. Grease and line two 8-inch round cake pans with parchment paper.
- In a bowl whisk together the flour, cocoa powder, baking soda, baking powder and salt and set aside.
- In a separate bowl add the egg whites, sugars, sour cream, milk, oil, vinegar and vanilla and whisk together.
- Add 1/2 the dry ingredients to the wet ingredients and mix it in. Pour in the hot coffee into the batter along with the remaining dry ingredients and mix until well combined.
- Divide the cake batter over the prepared pans and bake for approximately 25 minutes until a cake tester inserted into the middle of the cake comes out clean.
- Remove the cakes from the oven and run a knife along their edges to loosen them. Let them stand in their pans for 15 minutes before carefully turning them out onto a wire rack and letting them cool completely.
Frosting
- In a clean metal bowl of a stand mixer or other heatproof bowl, add egg whites and granulated sugar.
- Balance the bowl over a pot with 1 inch of gently simmering water, ensure that the bottom of the bowl isn’t touching the water. Whisk continuously as the egg whites warm-up and keep whisking until all the sugar has dissolved or the temperature reads 160°F (71°C) on an instant-thermometer. Don’t stop stirring or some egg whites may overcook on the edges of the bowl.
- Place the bowl of cooked egg whites in your stand mixer, or add them to your stand mixer bowl, fitted with the whisk attachment and beat on medium-high speed until a meringue with stiff peaks forms and the meringue has cooled down to room temperature. When you touch the sides of the bowl they shouldn’t feel warm.
- While the egg whites are beating, melt the chocolate. Place the chocolate in a microwave-proof bowl and melt it in the microwave for 20-30 seconds at a time, stirring after each time. Once about 2/3 of the chocolate has melted, remove it from the microwave and stir it to further melt it and combine it. Let the chocolate cool to room temperature (but don’t let it get too cold or harden again.)
- With the mixer on medium-high speed, feed in a cube of room temperature butter at a time, allowing it to incorporate fully before adding the next cube.
- At this point, the meringue can suddenly appear split or curdled. Just keep beating the mixture until it comes together into a thick and fluffy buttercream. This can take a lot of beating so don’t give up if it doesn’t seem to come together – it will. You want to keep mixing it until it loses the greasy look and it’s just thick and fluffy. See the notes for troubleshooting.
- Once the mixture is thick and fluffy, beat in the melted chocolate, salt, and vanilla until thick and fluffy.Switch to the paddle attachment and beat on low speed for 10 minutes to remove some of the larger air bubbles in the buttercream.
- Frost the cakes as desired. Leftover cake can be stored at room temperature for up to 2 days or be refrigerated for up to 4 days. The buttercream will stiffen in the fridge – let it come to room temperature to soften it again.
Notes
Swiss Meringue 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.