My Pastry Journal
By Tanya Novak, pastry chef
How pan dimensions, batter quantity and depth change heat transfer, baking time, centre doneness and cake structure—including why putting batter intended for a larger pan into a smaller pan can leave the centre under-set and prone to sinking.
King Arthur Baking states that when a cake recipe intended for a larger pan is baked in a smaller pan, more batter remains in the pan, heat takes longer to reach the center, and the cake can develop a slumped middle.
For more detail, these references explain the methods and ingredients. Follow the instructions for the exact product you use.