Preheat your oven to 350 degrees and line an 8×8 baking pan with parchment paper or spray well with non-stick spray.

To make the crust, add the gluten free flour, 1/2 cup granulated sugar, xanthan gum (if using), baking powder, salt, and ground cinnamon to the bowl of a food processor and pulse a few times to mix. Add the cold, cubed butter and vanilla extract. Pulse until the butter is incorporated with the dry ingredients and a pliable dough has formed.

Transfer 2/3 of the dough to the prepared baking pan and press into the bottom of the pan making sure it’s evenly distributed. Bake the crust for about 15 minutes (or until slightly browned).

While the crust is baking make the apple pie filling by mixing the sliced apples, fresh lemon juice, 2 tablespoons granulated sugar, cornstarch, ground cinnamon, ground nutmeg, and the pinch of cloves together in a large bowl. Make sure all the apples are coated with the spices!

When the crust is done baking, add the apple filling to the baking pan (the crust can be warm out of the oven). Layer the apples as evenly as possible. Cover the apples with the remaining dough by crumbling it over the top of the apples. Bake for 30-40 minutes or until the apple filling is bubbling around the edges of the pan and the crumb topping is beautifully browned.

Cool completely on a wire rack before removing from the pan. Cut into 16 squares and serve at room temperature.

Store leftover bars in an air-tight container in the refrigerator.