Slice enough apples to fill a casserole dish.
Sprinkle with cinnamon.
Mix equal parts of the following ingredients:
brown sugar [1/2 cup]
oatmeal [1/2 cup]
flour [1/2 cup]
and 1/2 part of the following:
butter [1/4 cup]
Sprinkle the mixture above on top.
Either microwave for 12-14 minutes, or bake at 375° F for 30-45 minutes.