Luckily, for this recipe eggs works out perfectly! You need 4 egg yolks for the custard and 4 egg whites for the cupcakes. When you do make custard or pudding, you are often left with egg whites. Don't ever discard your egg whites when you make pudding or custard! Save them to make egg white omelets or meringue cookies. You can also use it to make classic whiskey sour cocktail, coconut macaroons, cupcakes, meringue pie topping, angel food cake, and more. Make sure to store egg whites in a glass airtight food storage jar for about 2 days in the refrigerator!