Oven temperature and pan color can make the difference
When a cake bakes, the air bubbles you’ve beaten into the fat expand until the egg and flour proteins coagulate, the flour’s starch gelatinizes, and the cake’s structure sets. Larger bubbles mean an airy, coarser textured cake; smaller bubbles give a finer texture but also a denser one.
For finer textured cakes, try a slightly higher baking temperature (350°F). This will set the cake sooner and keep the bubbles from getting too big. For a lighter cake with a slightly more open texture, a slower oven (325°F) will help. The cake will need a few more minutes in the oven, but the lower temperature will give the bubbles more time to swell before the batter sets.
With cakes, the goal is a level top that’s as flat as a skating rink while muffins, in my ideal world, should peak like a volcano. In addition to oven temperature, choosing the right baking pan can help.
Heavy, dull, light-colored aluminum pans absorb less heat, and this makes them the very best choice for level cakes. Gray nonstick pans work all right, too. A dark pan, which absorbs more heat, can set the outside before the inside gets hot. The wet center will continue to rise and you may end up with a peaked cake.
For muffins to peak, gray pans are excellent. Black pans would also work, but if you’re not careful, they’ll burn the muffins.
A higher baking temperature (400° to 425°F) is key for a volcanic muffin. In this case, you want to encourage the outside to set fast and let the inside keep rising. If the muffins brown too fast, reduce the oven temperature for the last ten minutes of baking. Many muffin recipes say to heat the oven to 325° or 350°F, but you won’t get good peaks at these temperatures.