Combine the filling ingredients in a mixing bowl and set aside.
Grind 1/2 cup of the oats in a food processor until it forms a coarse flour.
In a small bowl, combine the oat flour with the remaining 1/2 cup of oats and the rest of the crumble topping ingredients. Mix until well combined.
Spoon the filling into a 24 ounce or larger baking dish.
Spread the crumble topping over the filling.
Bake for 30 to 40 minutes until heated through and lightly browned on top.
Leftover crisp can be covered and refrigerated for 3 days. Reheat it in a microwave or oven or enjoy it at room temperature.You can also make this apple dessert in advance. Bake it as stated in the recipe, then cover and reheat it when you're ready to serve.Tips for choosing apples:
The filling for this gluten-free apple crisp can be made with any of your favorite variety of apples.
I like to use Honeycrisp, Jazz, or Ambrosia apples.
But usually I go with whatever looks good in the store, especially if I can buy them in a bulk bag to save money.
You can also mix and match a few types or use whatever you have in your refrigerator.
Choose apples that feel firm and are free from blemishes.