Flour Butter Eggs Sugar Cocoa powder Milk & Water Coffee Sour cream Combine the butter, milk, water, cocoa powder and instant coffee in a saucepan. Cook until the butter is melted then bring the mixture to a boil. This not only “blooms” the cocoa (releasing its full, intense chocolate flavor) but it also melts our butter, which also helps the cake’s flavor. Remove your chocolate mixture from the stove and let it cool. Meanwhile, whisk sugars and dry ingredients together in a large heatproof bowl. Add the chocolate mixture to your dry ingredients and stir until smooth and combined. Stir in the sour cream, then add the eggs and vanilla and stir until smooth.