Follow the steps in order for the best result.
Begin by preheating your oven to 350°F (175°C). Grease a pie dish with cooking spray to prevent sticking.
In a large mixing bowl, combine the apple slices, sugar, water, cornstarch, 1 teaspoon of cinnamon, and nutmeg. Toss gently until the apples are evenly coated with the mixture. Set this aside.
Prepare the gluten-free oatmeal topping: In a separate bowl, lightly mix together the almond flour, gluten-free oats, brown sugar, 1 teaspoon of cinnamon, and softened butter. Use your fingers or a pastry blender to combine until the mixture resembles coarse crumbs.
Transfer the prepared apple mixture into the greased pie dish. Evenly sprinkle the crumbly oatmeal topping over the apples.
Bake in the preheated oven for approximately 25 to 30 minutes, or until the apples are tender, the juices are bubbling, and the topping is golden brown and crisp. Let it cool slightly before serving.
Serve your gluten-free apple crisp warm, at room temperature, or even chilled.