Preheat oven to 350 degrees and grease a springform pan.

In a medium mixing bowl, cream butter and sugar until light and fluffy.

Add eggs, one at a time, and beat until combined. Add flour and baking powder and mix until just combined.

Spread batter into springform pan. Top with apples, starting with a ring around the outside of the pan, moving toward the center, with lots of overlap.

In a small bowl, mix together sugar and cinnamon. Sprinkle over the apples.

Bake 60 minutes, until a toothpick comes out clean. If cinnamon sugar on top is still raw, broil 3-5 minutes until browned.