To prevent an under- or overdone cake, get an oven thermometer—it’s the best way to be sure your oven is calibrated correctly. Bake the cake in the middle (too close to the top or bottom can cause overbrowning). Gently close the oven door—a hard slam can release air bubbles trapped in the batter. To check for doneness, lightly press the center of the cake; if it springs back, it’s done. Or insert a wooden pick; it should come out clean.