Preheat the oven to 400 degrees Fahrenheit. Spray a 10-inch casserole/baking dish with cooking spray.
Gently combine the apples, cane sugar, lemon juice, vanilla extract, 2 teaspoons white rice flour, and salt in a large bowl. Fold mixture until apples are coated.
Transfer mixture to prepared baking dish and place onto a rimmed baking sheet and bake for 20 minutes. Remove from oven and carefully stir after 10 minutes, then return to oven to complete baking. Remove from oven when finished.
While the filling is baking, prepare the biscuits. Combine the white rice flour, oat flour, cane sugar, baking powder, and salt in a medium bowl. Whisk until ingredients are evenly incorporated.
Add 1/2 cup almond milk and the olive oil to the dry ingredients. Stir for 2-3 minutes; the mixture should start to thicken. Place bowl in the refrigerator and allow to chill for at least 10 minutes or until ready to top filling.
When the apple filling is ready and biscuit dough has chilled, use a tablespoon to drop 6-7 rounds of biscuit dough on top of filling. I like to loosely shape into rounds. This will not completely cover the filling. Using a pastry brush, use the remaining almond milk and brush the tops and edges of the biscuits with it and then sprinkle with coarse sugar (and whole oats if desired).
Bake for 22-25 minutes, or until tops of biscuits start to turn a light golden brown.
Cool apple cobbler for about 10 minutes before serving. Serve warm or at room temperature with vanilla ice cream.
Keep leftovers covered in the refrigerator for 2-3 days.