Preheat oven to 350°F.
In a large bowl, combine apples with all of the filling ingredients (lemon juice, 2 tbsp maple syrup, 1 tsp vanilla, 2 tsp cinnamon, 1/4 tsp nutmeg or pumpkin pie spice, 1 tsp arrowroot cornstarch).
Pour apples into a pie dish and spread evenly.
In a separate bowl, combine all the dry ingredients of the crumble (rolled oats, chopped walnuts, almond flour, walnut flour, salt) and mix well.
Once combined, stir in the maple syrup, MCT oil, and vanilla. Mix until well combined.
Spread crumble mixture evenly onto apples and place in the oven.
Bake for 45 minutes, covering with foil halfway if the topping starts to brown.
Let cool for at least 10 minutes and then serve with ice cream, whipped cream, or yogurt!
