Quick question for you all, when you make a sponge cake and say you are making an 8" sponge cake do you make a mix for a 10" cake or an 8" cake? I was always told to make more mix to get a thicker cake, but surely the cake wont be as airy and fluffy if there is more cake mix? Will the cake still rise enough if you make an 8" mix????
If there is baking powder or self-rising flour in the recipe, then thicker cake still rises.
For a thicker cake you will need to lower the oven temperature so that the middle cooks properly. If you bake 2" deep layers at 350F, then use 325F for a 3" deep layer. Line pan with 2 layers parchment if possible.
If you need a cake 4" deep, then bake in 2" deep increments. Deeper cakes take very much longer to bake and will rise, but be dry and overcooked on the outside.
In all cases use magic cake strips to prevent humps.