Preheat oven to 350˚F, and generously butter a 9-inch contour (rounded at the bottom edge) cake pan. The secret to the chocolate upside-down cake is in that pan – and, of course, what you put into it, and in what order.
Preheat oven to 350˚F. Grease a loaf pan, or several mini loaf pans. I used 4 mini-loaf pans, each with 1½ cup capacity, but you could use a regular loaf pan or even muffin tins, if you adjust the time accordingly (longer or shorter,
Peel the apples, and cut them into wedges. Melt the butter in a six-inch skillet over moderate heat. Add the apples, toss them to combine, and cook about 5 minutes, until they begin to soften. Add sugar, mix gently, and let cook until the sugar is caramelized.