1.  Pre-heat oven to 300 degrees F.  Crisscross two sheets of parchment paper to fit inside an 8 x 8 inch baking pan, so you can lift the bars out of the pan once they have cooled.

2.  In a medium sized bowl, mix together almond flour, salt and melted butter.  Stir in beaten egg and mix well to combine.

3.  Press the crust into the bottom of the lined baking pan.

4.  Bake for 18-20 minutes until just beginning to brown.  Take the crust out of the oven and increase the temperature to 350 degrees F.  

5.  For the filling, add blueberries and sweetener to a medium sized saucepan and bring to a simmer over Medium High heat.  Lower the heat and simmer until most of the berries have broken down 8 minutes.  Quickly whisk in Xanthan Gum and cook, stirring, until thickened, 1-2 minutes.   

6.  For the crumble topping, in a medium sized bowl, mix together almond flour, coconut flour, salt, and sweetener.  Stir in vanilla and melted butter and mix until chunks form.  You can use your hands to clump them into larger crumbles, if you'd like.

7.  Pour filling onto crust.  Sprinkle crumble topping on top.

8.  Bake at 350 degrees F for 15 - 20 minutes until the crumble topping is browned.

9.  Allow to cool in the pan for 1 hour before cutting into 9ths.