Untested - Chocolate Angel Food Cake

http://www.seriouseats.com/recipes/2013/01/chocolate-angel-food-cake-recipe.html
http://allrecipes.com/recipe/8252/chocolate-angel-food-cake-i/
http://www.marthastewart.com/334175/chocolate-angel-food-cake
http://www.tasteofhome.com/recipes/contest-winning-chocolate-angel-food-cake
http://www.food.com/recipe/chocolate-angel-food-cake-28138
http://www.melskitchencafe.com/ethereal-chocolate-angel-food-cake/

Most recipes call for 1/4 cup cocoa powder - I opted for the 1/3. Generally it looks like you want about a cup of flour for a regular cake, and if adding cocoa flour, subtract the amount of flour by the amount of cocoa used. Since I'm adding a third and using three quarters of a cup of flour, I hope it doesn't screw things up! If it does, I will eat the cake and try again!

1/3 cup cocoa powder
1 1/4 cups granulated sugar
3/4 cup flour
1/4 teaspoon  salt
12 large egg whites
1-1/2 tsp cream of tartar
1-1/2 tsp vanilla
Set the oven rack to the middle position and preheat the oven to 325F.
In a medium bowl, whisk together the flour, cocoa, sugar and salt.
If you have a mixer, place the egg whites and the vanilla into the mixer bowl. Beat the egg whites and vanilla on medium-high until the mixture is just frothy, about 1 minute.
Sprinkle in the cream of tartar and continue beating on medium-high until soft peaks form, another 2-3 minutes.
Slowly add the sugar, waiting between additions until it's fully incorporated.
Continue beating until the whites are stiff and glossy but not dry, about 3-5 minutes.
Gently fold the dry ingredients into the beaten egg whites, gently to avoid breaking too many air bubbles in the egg whites.
Pour the batter evenly into an ungreased angel food cake pan and smooth the top.
Bake for 40-45 minutes, until the top of the cake is golden brown, the cake springs back when lightly touched and the cracks are dry to the touch.
Once baked, put the cake on a cooling rack for 5-10 minutes, then upside down to cool completely (about 4 hours).
Once cooled, slide a knife around the edges of the pan and gently remove the cake.

CHOCOLATE FLUFF FROSTING:
2 cups heavy cream
1 cup sifted confectioners' sugar
1/2 cup baking cocoa
Dash salt
In a large bowl, beat the cream until it begins to thicken.
Add the sugar, cocoa and salt; beat until stiff peaks form.