• Preheat oven to 350ºF. Spray an 8x8-inch baking dish with cooking spray or line it with parchment paper. Set aside.

Make the Crust

• Place all of the crust ingredients into a large bowl. Use a spatula (or your hands) and stir together until a crumbly mixture forms that can hold its form.
  
• Transfer the crust mixture into the prepared baking dish. Use a spatula to flatten the crust mixture evenly into the pan. The more tightly packed the mixture, the better.
• Bake until golden brown, about 15-17 minutes. Keep the oven on while you make the filling.

Make the Apple Filling

• While the crust is baking, make the apple filling. Begin by cooking down the apples. Placing all of the filling ingredients into a medium-size pot set over high heat. Bring the mixture to a boil.
  
• Once boiling, reduce heat to low and simmer until the filling has reduced and thickened, about 7-9 minutes.* Stir every so often.
• Remove the pot from the heat. Use a fork to mash the apples so that the filling is a combination of apple mash and apple chunks.
• Pour the apple filling over the baked crust. Use a spatula to evenly spread it out. Set aside.
  

Make the Crumble Topping

• Place all of the ingredients for the crumble topping into a medium bowl. Use a fork (or pastry blender) to cut in the ingredients until a crumble forms.
• Evenly sprinkle the crumble topping on top of the apple filling.
• Bake until the crumble topping is golden brown, about 26-28 minutes.
• Remove from the oven and let cool for 10-15 minutes. Transfer the bars to the refrigerator and chill for at least an hour before slicing and serving.