Mix all the ingredients for the cocoa mixture in a deep bowl.
Mix well and pour the egg white mixture into the cocoa one.
Stir carefully with a spatula, so that the egg whites don't deflate.
Pour the cake mixture into a form covered with baking paper and bake 10-15 min. in a preheated 320°F (160°С) oven. Then lower the heat to 284°F (140°С) and bake about another 35 min. or until a toothpick comes out dry when you poke the cake.
Serve with a glass of milk.