Preheat oven to 350 F
Lightly grease a 9 or 10-inch deep dish pie pan or cast iron skillet.
In a large bowl, combine apples, lemon juice, 1 TBSP maple syrup, vanilla, tapioca starch, 1 tsp cinnamon and 1/4 tsp salt until well mixed. Pour apple mixture into prepared pan, scraping down sides to get all the juice into the pan. Add walnuts, coconut, coconut flour, butter or oil, and remaining maple syrup, cinnamon and salt into the same large mixing bowl and stir to thoroughly combine. Crumble this mixture evenly over the apples. Bake for 25-30 minutes, until apples are bubbly and top is golden brown.