Preheat oven to 375 degrees Fahrenheit. Line an 8 inch by 8 inch pan with parchment paper.

First, make the crumble topping.

Add all crumble topping ingredients to a mixing bowl. Use your hands, a pastry cutter or fork to incorporate butter into mixture. Mix until a crumbly mixture forms. Place bowl in fridge.

Next, make the shortbread crust. Add cold butter, brown sugar and granulated sugar to a stand mixer bowl. Beat until no clumps of butter remain.

Add in vanilla extract, flour and cinnamon to bowl. Stir until combined. Place dough into lined pan. Press into an even layer.

Bake shortbread crust for 15 minutes. Then remove from oven.

While shortbread crust bakes, make apple filling. Peel and core apples. Slice into ¼ inch thin slices.

Add all apple filling ingredients to a skillet over low heat. Stir gently to combine and stir occasionally for 5 minutes or until apples have softened. If needed, add more water to the skillet to prevent burning.

Once shortbread crust has finished baking, pour apple filling on top. Spread into an even layer. Then, top apples with crumble topping.

Bake for 35 to 36 minutes. Remove pan from oven. Allow to cool completely before slicing and serving.