Baking a larger batch in 9-inch pans: A double batch of this cake works in three 9-inch cake pans -- just watch your bake time after 15 minutes and be sure not to overbake! Cake Flour Substitute: You can make a cake flour substitute using all-purpose flour and cornstarch! Just use your kitchen scale to measure out 164g of all-purpose flour and sift it with 24 grams of cornstarch. Or if you don't have a kitchen scale, measure out 1 ½ cups of flour using the spoon-and-level method, then remove 3 tablespoons of it and replace it with 3 tablespoons of cornstarch. Sift them together and add to your dry ingredients as usual! Softening butter: If you're in a rush, soften your butter in seconds by popping it in the microwave! Heat your stick of butter on high for about 20 seconds, rotating every few seconds. Buttermilk Substitute: If you don’t have buttermilk, feel free to use whole milk, replacing 2 teaspoons of the milk with vinegar. This will create the acidic effect of buttermilk to help your white cake layers come out even more moist and tender.