Preheat oven to 350 degrees F.

In a bowl, combine filling ingredients.

Sprinkle xanthan gum lightly while mixing to prevent clumping.

In another bowl, combine walnuts, coconut flour, flaxseed meal, sweetener, and sea salt.

Add melted butter and mix until crumbly.

Set aside 1/2 cup of crumble.

Grease a 9-inch glass pie dish and press the crumble into the bottom.

Spread the fruit mixture evenly over the crust.

Sprinkle the remaining crumble over the top.

Bake for about 20 minutes covered with tinfoil, then uncover and bake for an additional 10-20 minutes until browned.

Allow to cool completely in the refrigerator before serving.