This cake is a bit fancy. Don’t be intimidated by the whipping, or stiff peaks, because once you know how to do it, you will always have that knowledge to get you through baking with egg whites. http://www.thekitchn.com/a-visual-guide-soft-peaks-firm-115557
This is just a chocolate version of an angel food cake, so sprinkle a little powdered sugar on top and you will be the toast of the town. Or your house, or your work place, or anywhere you take it. *Note-make sure you sift and fold when directed, if you over whip or over whisk/stir you will get a dry, hard cake.
1 pound or 8-10 large egg whites (use scale for exact measuring)
2 tsp cream of tarter
4 T cocoa powder
2 oz warm water
2 tsp vanilla
1 3/4 cup sugar
3/4 cup cake flour sifted after measuring
1/4 tsp kosher salt
Preheat oven to 350 degrees and grease an angel food pan
Whisk egg whites in stand mixer on medium speed until foamy, add cream of tarter and let beat until stiff peaks (see link above or picture below)
Once egg whites are at stiff peaks, add a large spoonful of egg whites to the cocoa mixture and fold gently until combined. Add this back into remaining egg whites and fold gently. Sift flour mixture over egg whites, again folding gently until combined. Pour into prepared pan and cook for 40-50 minutes or until center comes out clean with a clean knife or toothpick
Let cool upside down (top will most likely have cracks, this is okay) and sprinkle some powdered sugar on top to cover the cracks or eat it alone-either way it is too good to be true!
Can be kept wrapped tightly for up to five days