There is nothing more frustrating than laboring over a cake and then having it stick to the pan. Most of us butter and flour cake pans to prevent sticking, and most of the time this works. But to be absolutely certain the cake comes out of the pan with its surface perfectly smooth, butter the inside of the pan, cover the pan bottom with a round of buttered parchment paper, and then flour the inside of the pan and the paper. Don’t cut the round of paper any larger than the pan; if it extends up the sides around the edges it will make a rough edge on the cake. On the other hand, it’s fine if the parchment paper is slightly smaller than the cake pan. To butter and flour a cake pan, brush the inside of the pan with room-temperature butter, put a handful of flour in the pan, and rotate it until the bottom and sides are coated with flour. Invert the pan and tap it against the work surface to shake out any excess flour.