Temperature has a big effect on how your cupcakes and cakes will rise during baking. When your oven temperature is too high for the type of batter you are using, your cupcakes or cake will peak/dome and crack during baking. But did you know that foil cupcake cases can have a similar effect?
Foil cases retain more heat than paper ones and this extra heat is then transferred to the batter causing it to peak and crack during baking. You can see here how the cupcake baked in the foil case (left) has risen more dramatically when compared to the cupcake baked in the paper case (right), which has risen evenly and without peaking.
The good news is that foil cases are still fine to use, but if you would prefer a more even, less ‘peaky’ rise, just drop your oven temperature by about 10°C and this will reduced the heat transferred by the foil cases.