I think Jeanne’s on to something when she says don’t fill them too full. I just baked the All-American Chocolate Cake recipe in a 6x2 pan, filled too full (quite close to the top). I knew this wasn’t ideal, but the batter was left over from a large batch of mini-cupcakes, and I was just trying to use it up.
The texture difference between the over-filled pan and the properly filled cupcakes was quite noticeable. The 6x2 cake became denser in texture near the bottom, and was drier and more crumbly due to the overbaking necessary to get the center done. The batter was identical in both the cupcakes and the 6x2, from the same bowl, and baked in the same oven, so the inferior result was due to the overfilled pan.
Patrincia’s trick of using a flower nail to conduct heat to the center might help, but I think a deeper layer might also need more structure, which compromises the tenderness of the cake.
Sometimes it takes a lot of mistakes to fully appreciate how perfect Rose’s recipes are!