Whip the egg whites with a mixer until frothy. Add the cocoa powder, sugar and flour (first measures cocoa powder and sugar). Beat on high until glossy and medium stiff peaks form.
In bowl beat remaining ingredients. Beat about 5 minutes.
Lightly fold the egg whites into the yolks (a third at a time) until its all incorporated.
Pour into muffin pans lightly sprayed with cooking spray.
Bake at 300 degrees for 30 minutes. Turn off the oven and let sit in the oven for another 10-15 minutes.
Remove from pan and let cool before frosting if you want.