Preheat oven to 375°F and prepare a 9 x 13 inch baking dish by lightly greasing with coconut oil. The large pan will allow the biscuit crust to brown and get crispy because more surface area is exposed to the hot air than in a pie dish.
Place the sliced fruit in the 9 x 13 inch pan. In a small bowl, whisk together the tapioca starch and coconut sugar until combined. Sprinkle the mixture over the fruit, then stir it in. Mixing the sugar and tapioca together in advance will prevent the tapioca from clumping.
Mix in the vanilla extract, if using.
Bake for 10 minutes.
Meanwhile, in a large bowl, whisk together almond flour, sweet rice flour, oat flour, coconut sugar, baking powder, salt, and optional baking soda.
Using a pastry cutter or two knives, quickly cut the coconut oil into the flour until the largest bits of coconut oil are no larger than small peas and the dough is crumbly.
Add almond milk and fold together until just combined (do not over mix). Dough will be slightly sticky.
Pull the baked fruit out of the oven and increase the oven temperature to 400°F.
Use a large spoon or ice cream scoop to drop the dough evenly over the top of the fruit layer in as many biscuits as you like. Smaller biscuits, spread out, will get crisper than large ones. Spaces between the biscuits will allow moisture to evaporate from the fruit mixture during baking.
Return the cobbler to the oven and bake until the biscuits have golden brown peaks and the fruit mixture is bubbly, 35-40 minutes.
Remove from heat and let cool at least 15 minutes. Then serve with scoops of coconut milk yogurt or your favorite ice cream. The fruit mixture will thicken up as it cools.