Ingredients:
1/2 cup (113g) unsalted Butter
2 1/2 cups (600ml) Milk
1 cup (115g) Flour
1/2 cup (43g) Cocoa Powder
4 Eggs, separated
4 drops White Vinegar *see head note
1 3/4 cups (210g) Confectioner's Sugar
2 Tablespoons (30ml) Espresso or Strong Coffee, lukewarm
1 teaspoon (5ml) Vanilla Extract
extra confectioner's sugar for dusting
optional-fresh berries for garnish
Directions:
Preheat the oven to 325°F. Lightly butter or grease a 8"x8" baking dish.
Melt the butter and set aside to slightly cool. Warm the milk to lukewarm and set aside.
In a separate bowl, whisk together the flour and cocoa powder for 20 seconds. Set aside.
Whip the egg whites with vinegar to stiff peaks. Set aside.
Beat the egg yolks and sugar until light. Beat in the melted butter, espresso, and vanilla extract for about 2 minutes or until evenly incorporated.
Mix in the flour/cocoa into the batter until evenly incorporated. Gently whisk/beat in the milk until everything is well mixed.
Fold/gently-whip in the egg whites, 1/3 at a time. Repeat until all of the egg whites are folded in.
Pour the batter into the prepared pan and bake for 50-60 minutes or until when you gently shake the cake, it is slightly jiggly but is no longer runny jiggly (I know it sounds weird, but that is the best way we can think of describing the sensation).
Allow cake to completely cool before cutting and then dust with confectioner's sugar. Garnish with fresh berries if desired.