Shortbread Crust

Preheat oven to 350º F. Line an 8×8 baking dish with parchment paper, leaving extra hanging over the baking dish, spray with non-stick cooking spray.

In a large mixing bowl, with a hand mixer, beat together the butter and sugar until light and fluffy, about 2-3 minutes. Add vanilla and mix. Add flour and mix until combined and the dough is crumbly.

Press dough evenly into the bottom of the prepared baking dish. Bake for 12-14 minutes, until mixture, is slightly puffed. Remove from oven and set aside.

 Filling

In a large bowl, combine apple slices, flour, and sugar. Toss mixture until apples are evenly coated. Place apples on baked crust.

Crisp Topping

In a medium bowl, mix together first five ingredients. With a pastry blender or your fingers, cut in butter until mixture is crumbly. Stir in pecans. Sprinkle the topping over apples in an even layer.

Bake uncovered at 350º F for 45 minutes, or until topping is golden and apple mixture is bubbly. Top loosely with foil if the topping gets too brown during baking. 

Let cool, lift the bars from the baking dish using the extra parchment paper at the ends as handles, and cut into bars.