You can also line the pan with parchment paper with a 1” overhang all the way around. Add the parchment paper as soon as you take the hot pan out of the oven (be careful) then carefully dump the batter on top of the parchment. The weight of the batter will force the parchment to line the pan.
This is the pan I use (and love!) 12″ cast iron skillet
If you want to make 2 cakes, use 2 of these 6 1/2″ cast iron skillet pans!