I need a recipe for chocolate biscuit de savoie using cocoa powder. I am talking about half recipe from the TCB that fits in one 9 inch round pan.
I have come up with estimates for tweaking the original recipe but need advice from baking forum. Similar to chocolate genoise, I plan to increase cake flour to 3/4 cup and replace cornstarch with 1/4 cup cocoa, dissolved in hit water. As per original recipe, I need 4 separated eggs, but should I use 5 eggs similar to chocolate genoise recipe since they say cocoa deflates the batter? IN this case, the whipped egg whites help the batter structure, so I am wondering if I can skip the extra egg.
Also, with cocoa powder, should I add extra sugar to batter? Original recipe requires 1/2 cup sugar.