Fill a baking dish with apples and sprinkle cinnamon to taste over the apples.
Mix walnuts, pecans, and brown rice flour together in a bowl. Add grapeseed oil, maple syrup, and cinnamon; stir until completely combined. Spread nut topping over apples.
Bake in the preheated oven until apples are cooked through, 30 to 40 minutes.
