01 - Preheat the oven to 350°F. Lightly grease a 2-quart baking dish with butter or cooking spray.
02 - Combine peach slices, granulated sugar, flour, cinnamon, nutmeg, lemon juice, and salt in a large bowl. Toss thoroughly until peaches are evenly coated. Transfer mixture to the prepared baking dish.
03 - Whisk together flour, oats, brown sugar, cinnamon, and salt in a separate bowl. Add cold cubed butter and blend using fingers or a pastry cutter until mixture forms coarse, pea-sized crumbs.
04 - Sprinkle crumble mixture evenly over the peaches. Bake for 35 minutes until topping is golden brown and fruit filling is bubbling around the edges.
05 - Let the crumble rest for at least 10 minutes before serving. Best served warm with vanilla ice cream or whipped cream.