Peel and slice your apples. Use any kind you like. I like to use at least two kinds for more flavors. Place the apple slices in a large mixing bowl.
Add the lemon juice, maple syrup, cornstarch, cinnamon, nutmeg and salt and mix until well combined.
Pour the apple slices into a 9" x 13" baking dish. Cover with aluminum foil.
Bake in the preheated oven for 30 minutes.
Meanwhile, while the apples are baking, prepare the topping.
In a medium mixing bowl, combine the oats, whole wheat flour, all purpose flour, cinnamon and nutmeg and mix well. Stir in the maple syrup and set aside.
After 30 minutes, take the apples out of the oven and remove the aluminum foil. Using your fingers to break up any clumps, spread the oat crumble on top of the apples. Make sure there aren't any large pieces.
Bake uncovered for 25 minutes. Take the crisp out of the oven and let rest for 5-10 minutes before serving. Feel free to add some vegan whipped cream or ice cream on top.
Store in an airtight container in the fridge for up to 4 days.
Notes
You don't want to have big chunks of the crumble mixture. As there is no oil or vegan butter in this recipe, the topping will not be too crisp. If you have big chunks, it will be chewy.
Try mixing different kinds of apples. I like mixing a few sweeter apples with a couple tart apples together for this recipe.