Dice up your apples—enough to fill your pan. I did these fresh but I freeze apples cut up in quart bags and I can use 3 full bags to fill the pan.
Sprinkle 1 cup sugar, 1 tsp cinnamon and 2 T of flour on top of the apples to sweeten them. These apples were not super sweet so we added a little more than usual. 
Spread it out with your fingers to cover the apples.
Melt 1 cup butter in microwave and add 2 cups brown sugar, 2 cups oatmeal and 1 cup flour. Mix well and sprinkle on top.
Bake 350 for an hour or until crispy browned. 
