Q. If I bake double the recipe should I use double the baking powder?
Charlotte White says: Yes. When doubling a cake recipe, make sure that you double all of the ingredients accurately. The only thing that you should not double is the baking time in the oven; a doubled cake will need a little more time (maybe 50% or so more) but will not need exactly twice the amount of time. You will need to keep an eye on the baking.