A couple Christmases ago, I saw the Pancake Puff pans in all the housewares stores, and ended up wrapping one up to put under the tree. I read a good discussion online about how the food science involved is similar to waffles - fried on the outside and steamed on the inside, use of separated eggs with beaten whites folded in at the end for more lightness. I modified the online aebleskiver recipe to be gluten free and checked it against the proportions I've used for gluten free waffles. Basically, this is a thicker batter than I use for waffles or pancakes, but otherwise, quite similar.