Preheat oven to 350 F. In a large bowl, whisk together the flour, oatmeal, and brown sugar, cut in the cold butter with a pastry blender until pea sized. Reserve 2 cups of the crumb mixture. Press the remaining mixture into the bottom of a greased 9 x 13 inch pan. Crust will be crumbly. Set aside.
Dice the apples and toss with the sugar, cinnamon and nutmeg. Arrange apples over the top of the crust. Drizzle 1/3 cup of caramel sauce over the apples. Top with the remaining crumb mixture.
Bake at 350 F for 40-45 minutes or until apples are tender and crust is lightly browned. Let cool completely, drizzle with remaining caramel sauce and cut into bars. Store in the refrigerator.