Preheat oven to 350 °F. Grease a 10.5 X 7.5 rectangle baking dish (or something similar) with avocado oil (or oil of choice).
Peel and slice the apples, then place into a medium-sized mixing bowl, juice a lemon over the apple slices and then toss to coat. Add cinnamon, nutmeg, and salt. Toss (or stir) until coated.
Place apples in the baking dish. Add pecans to the bowl the apples just came out of and crush them with the bottom of a jar/glass. Once crushed, add the rest of the ingredients listed under the crumble EXCEPT the butter. Stir together the dry ingredients, then add melted butter and stir again.
Add crumble over the top of the apples and then drizzle with maple syrup (roughly 2-3 tablespoons). Bake for 30-35 minutes (mine typically takes 33) on the middle rack or until golden brown and fragrant.
Remove from oven and let cool for 5-10 minutes. Serve with a scoop of ice cream, whipped cream, or a drizzle of date caramel.