Yes, but proceed with caution—when doubling cake batters, the leavening agents (baking powder and/or baking soda) should NOT be completely doubled, as this throws off the baking science. If doubling the cake, use only 5 1/2 teaspoons of baking powder. Note that when doubling cakes, things can just go awry—it's harder to evenly incorporate a larger amount of ingredients—so if you want to be 100% safe, you are best off baking the cake twice (annoying but worth it for perfect cake).