- 1/2 cup unsalted butter
- 2 1/2 cups milk
- 1 cup flour
- 1/2 cup cocoa powder
- 4 eggs, separated
- 4 drops white vinegar
- 1 3/4 cups confectioner's sugar
- 2 tbsp espresso or strong coffee, lukewarm
- 1 tsp vanilla extract
- extra confectioner's sugar for dusting
- berries for topping
Preheat your oven to 160°C and and lightly butter a 20 x 20 cm baking pan (or any size you prefer).
Melt the butter and leave it aside to cool. Warm the milk to lukewarm and leave it aside.
In a bowl, whisk together the flour and cocoa powder until combined, and leave it aside.
Using a stand mixer, whip the egg whites with the vinegar until stiff peaks form, and leave it aside.
Beat the egg yolks and sugar until light. Then beat in the melted butter, espresso, and vanilla extract until the mixture is evenly combined.
Mix in the flour / cocoa mixture into the batter, mixing until it's all incorporated. Then add the milk and gently whisk until everything is well mixed. (Your batter will be unusually liquidy).
Gently fold in the egg whites, 1/3 at a time and slowly whip until the mixture is somewhat homogenous. (The batter will still feel unusually liquidy).
Pour your batter into the prepared pan and bake for 50-60 minutes. Allow the cake to completely cool before removing it from the pan and cutting it. Dust with confectioner's sugar and garnish with berries.