Preheat the oven to 350°F. Lightly grease a 9” square or round casserole dish with coconut oil. Set aside.
Place the mixed berries in a large bowl. Add the tapioca flour, coconut sugar, cinnamon, and vanilla extract. Toss to coat all of the berries and pour into the prepared pan.
2 pounds (about 6 cups) mixed berries, 2 tablespoons (14g) tapioca flour, ¼ cup coconut sugar, ¼ teaspoon cinnamon, 1 teaspoon vanilla extract
For the crumble topping, combine the almond flour, coconut flour, cinnamon, rolled oats, maple syrup, coconut oil, and walnuts in a mixing bowl. Stir until the dry ingredients are completely moistened and then crumble evenly over the berries.
1 cup (96g) almond flour, 2 tablespoons coconut flour, ¼ teaspoon cinnamon, ½ cup gluten-free rolled oats, ¼ cup maple syrup, ¼ cup coconut oil, ¼ cup nut of choice
Place the pie on a baking sheet and bake 45-50 minutes or until the crisp is bubbling, and the crumble is golden brown on top. Tent with foil if the pie starts to brown too quickly!
Serve warm or let cool before serving. I recommend serving with dairy-free vanilla ice cream or whipped coconut cream. Keep any leftovers stored in the refrigerator.