Preheat oven to 350 degrees F. Coat a 9-inch x 9-inch baking dish with non-stick cooking spray.
In a medium mixing bowl, stir together the oats, flour, brown sugar, baking powder, cinnamon, nutmeg, and salt until well combined. Pour in butter and use a fork to stir the butter into the oat mixture until everything is evenly moistened.
Set aside 1/2 cup of the oat mixture. Pour the rest of the oat mixture into the prepared dish, and use your hand to press it into an evenly, tightly packed layer. Bake for 15 minutes.
Remove bars from oven. Pour pie filling over the cooked oat crust. Use a spatula to carefully spread the pie filling into an even layer, covered the crust completely. Sprinkle the bacon evenly over the top of the pie filling. Sprinkle the remaining oat mixture over the bacon in an even layer.
Bake for 12 to 15 mins or until the crumb topping is cooked through.
Remove from oven and let cool for at least 30 minutes before cutting into 16 small bars or 9 larger bars. (If you want to eat the bars sooner, they will be on the crumbly side, which makes them perfect for putting into a bowl and topping with vanilla ice cream.)
If you don't have prepared apple pie filling available, you can substitute applesauce in its place.