Cut out a 10-inch round of parchment or wax paper. Moisten the paper and then lay it on top of the potatoes. Cover with a lid that fits inside the skillet and cook the galette over moderate heat for 8 minutes, or until golden around the edges when the paper is peeled back. Transfer the covered skillet to the oven and bake for 15 minutes, or until the potatoes are just tender when pierced with a knife. Remove the lid and parchment and bake for 7 minutes longer, or until the top is browned. Run a spatula around the edge of the skillet and shake to loosen the galette. Invert a plate over the skillet, flip and turn out the galette.