Step 1Heat the oven to 450 degrees.
Step 2Combine 2 tablespoons of melted butter with the eggs, milk, granulated sugar, vanilla, cinnamon, salt and flour. Mix the batter by hand or in a food processor. Set aside.
Step 3Heat the remaining 3 tablespoons of butter with the apple slices in a 10-inch oven-proof skillet until the apples are sizzling and slightly cooked. Pour in the batter. Sprinkle the top with brown sugar and bake until well browned and puffed, 20 to 25 minutes. Dust with powdered sugar. Cut into wedges and serve immediately.