1) Heat oven to 350°F Lightly grease a 15- by 10- by 1-inch baking pan. Prepare Crumb Topping; set aside.
2) In medium bowl, combine flour, oats, and sugar. With pastry blender or fork, cut in butter until mixture is crumbly.
3) In medium bowl, combine oats, 1 cup flour, the brown sugar, baking powder, and salt; cut in butter until crumbly. Stir in beaten egg. Spread mixture evenly in pan.
4) Toss apples with sugar, remaining 1/4 cup flour, and the nutmeg. Spread apples over oatmeal layer. Sprinkle Crumb Topping in a diagonal pattern over apples. Bake 30 to 35 minutes or until apples are tender. To yield 40 bars, divide the 15-inch-long side into 8 sections. Divide the perpendicular 10-inch-long side into 5 sections.