Preheat oven to 350 degrees.

For the crust: add the flour, sugar, salt, and baking powder to a bowl and mix. Then add in butter and cut in with a pastry blender until you have pea sized crumbs.

Mix in the beaten egg until combined.

Spray a 9 x 9 or 9 x 13 inch pan (depending on the thickness you want) with non-stick cooking spray. Press 2/3 of the crust mixture into the bottom of the dish, set aside the remaining crust mixture.

In a bowl, combine all of the filling ingredients together until well combined. Spread filling mixture over the pressed crust. Sprinkle the remaining 1/3 crust mixture over the apples.

Bake for 40 minutes for the 9 x 13 pan or 50 minutes for the 9 x 9 pan. Then allow to cool.

Once cool, combine the the glaze ingredients together in a bowl. If needed add a splash of milk to thin if too thick. Pipe frosting over the cooled bars to make a nice drizzle. Allow frosting to set and serve. Makes 9 - 12 bars.