This cake can also be made in a regular 9-inch (23cm) cake pan, one that is fine to heat on the stovetop if you don’t have a cast iron skillet. (If you don’t have a regular cake pan that can be put over direct heat, such as a glass or ceramic mold, you can heat the butter and brown sugar in a saucepan and pour it into whatever pan you’re using.) Don’t use a springform pan as the topping will almost certainly leak.
If using frozen cranberries, no need to defrost them before using them. If you want to substitute other fruits, just arrange them in a pinwheel or haphazard design over the layer of brown sugar topping in place of the cranberries. If using slices of raw pineapple, sauté it first for a few minutes, until heated through.
Storage: The cake is best made and served the same day, warm if possible. To rewarm it, use some of the techniques mentioned in the post. It is also good served at room temperature. This cake isn’t a good candidate for freezing. But if you must, wrap it well and freeze it for up to two months.