Preheat oven to 350 degrees F (175 degrees C). Line the outside of a 9 inch springform pan with foil to catch drips.
Spread butter evenly into a 9 inch springform pan. Sprinkle with sugar. Arrange apple slices into an overlapping pattern over sugar layer. Cover apples with pastry, trimming sides if necessary. Place pan on a baking sheet.
Bake in preheated oven for 1 hour, until pastry is golden brown. Allow to cool slightly, then release sides of pan. Place a large plate over pastry, then invert so apple layer is on top. Remove bottom of pan and serve.
