Prep: Preheat the oven to 350F. Grease a 10” cast iron skillet (or similar sized pan) with butter or cooking spray and set aside.
Make the Crumble: Add the melted butter, brown sugar, cinnamon, and salt to a small bowl. Mix well, until the brown sugar has dissolved. Add the flour to the bowl and mix gently until a thick, crumbly mixture forms. Set aside.
Fruit Filling: Add the apples, flour, sugar, cinnamon, ginger, nutmeg, cardamom, vanilla, lemon juice, and salt to the prepared cast iron pan. Mix well with a spatula until all of the apples are evenly coated, then spread the slices out to form an even layer across the bottom of the pan.
Assemble: Use your hands to crumble the crumble evenly over the fruit, leaving some pieces bigger and some smaller.
Bake: Bake in the middle rack of the oven for 45 to 50 minutes, until the fruit is bubbly and the crumble has browned. Remove from the oven and set aside for 5 to 10 minutes, to allow the filling to set.
Serve: Serve warm topped with vanilla ice cream, or as desired. Store any leftovers in the refrigerator for up to 5 days.