Scrape down sides of bowl, add sour cream, and beat until combined. Scrape down sides of bowl. Add egg and vanilla and beat until combined. Transfer batter to an airtight container and refrigerate ...
Mix butter and cocoa 4. Then mix in cake flour, sugar, eggs, and vanilla flavoring. Mix until combined be careful not to over mix-batter can be thick. You can add nuts as well but not required. 5.