01 - Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
02 - In a skillet over medium heat, melt 2 tablespoons of unsalted butter. Add the diced apples, granulated sugar, brown sugar, cinnamon, nutmeg, lemon juice, and salt. Cook while stirring occasionally until the apples soften and the juices thicken, approximately 6–8 minutes. Allow the mixture to cool slightly.
03 - In a mixing bowl, combine the all-purpose flour, rolled oats, brown sugar, and cinnamon. Add the cubed cold butter and rub the mixture with your fingertips until it resembles coarse crumbs. Spread this crumble mixture onto a small baking sheet and bake for 7–8 minutes, or until it is lightly golden. Let it cool completely.
04 - Lay the flour tortillas flat. Divide the cooled apple filling evenly among the tortillas, spooning it along the center of each. Sprinkle some of the cooled crumble topping over the apple mixture, reserving a small amount for the final garnish.
05 - Fold the sides of each tortilla inward to cover the filling, then roll them up tightly to fully enclose the filling.
06 - Place the rolled wraps seam-side down on the prepared baking sheet. Brush the tops with the melted butter. Combine the granulated sugar and cinnamon, and sprinkle this mixture evenly over the tops of the wraps.
07 - Bake for 12–15 minutes, or until the wraps are golden brown and crisp. Allow them to cool briefly, then sprinkle with the reserved crumble topping before serving.