Cut up the granny smith apples, measure 6 cups worth of chunks, and place in a large bowl

Add the lemon juice, brown sugar, cinnamon, salt, and cornstarch for the filling and stir to combine

In a separate bowl, whisk together the brown sugar, oat flour, oats, and salt

Melt butter and coconut oil until liquid, then add to the remaining crisp ingredients

Use a rubber spatula to mix until the crisp topping resembled wet sand

Pour the apple filling into a small baking dish or pie pan, then spread the crisp topping evenly over the apples

Bake the gluten free apple crisp at 350 degrees for 50 - 60 minutes, or until the crisp is golden browned and the apple filling is bubbly

Serve warm topped with vanilla ice cream