1. In a medium mixing bowl, whisk together the almond flour, salt, and xanthan gum until well combined.
2. Add in the coconut oil and butter and cut together using a pastry cutter (or knives or forks) until a thick sand-like texture develops.
3. Add in 4 tablespoons ice cold water and use a wooden spoon to mix together until a dough begins to form. If the dough is too dry to hold together, add water one tablespoon at a time until it will hold together.
- If using tartelette pans use hands to form the dough into a disk, wrap the dough in parchment paper, place in a plastic bag, and refrigerate for 30 minutes.
- If using a muffin tin, divide the dough into nine pieces, place liners in the muffin tin (or grease), and press the dough from the bottom outward and upward to fill the entire tin (or muffin liner), spreading evenly along the bottom and sides.
4. Preheat the oven to 350º F just before rolling out the crust, or immediately after filling the muffin tins.
5. For the tartelettes: Divide the dough into six equal portions. Roll out each portion to about 1/8-inch thick and gently place in tartelette pans. Remove extra dough that hangs over the edge of the tartelette and use to patch any holes in the bottom of the dough.
6. Place tartelette pans with crusts on a baking sheet and bake in the preheated oven for 13 minutes. For the muffin tin, place the tin right on the oven rack and bake for 10-12 minutes.
7. While the crusts are baking, start on the filling. In a large skillet over medium heat, add the berries, maple syrup and salt and bring to a boil. Boil for about 10 minutes, until juices begin to thicken. Sprinkle in the tapioca flour and stir until well combined. Continue to cook over medium-low heat until thick, about 2 minutes.
8. When the crusts have just started to brown on the outer edges, remove from the oven. Divide the filling evenly among the crusts and return to the oven to finish baking, about 10 more minutes, or until the crust is golden brown on the edges.
9. Let tartelettes or muffin-tarts cool to the touch, at least 20 minutes. Remove from pans, top with vanilla ice cream, and serve.