Preheat your oven to 350°F (175°C) and lightly grease a baking dish.
Combine sliced peaches with granulated sugar and lemon juice in a large mixing bowl. Toss gently to coat all the fruit evenly. Let it sit for a few minutes to enhance the flavor and draw out some juices.
Transfer the peach mixture into your prepared baking dish, spreading it out into an even layer.
In a separate bowl, combine the flour, rolled oats, brown sugar, and cinnamon. Add the cold, cubed butter and use a pastry cutter or fork to cut the butter into the mixture until it resembles coarse crumbs.
Sprinkle the crumb topping evenly over the peaches, covering the surface completely.
Bake the crumble in the preheated oven for 35-40 minutes, or until the topping is golden brown and the filling is bubbling at the edges.
Remove the crumble from the oven and let it cool slightly for about 10 minutes. This allows the juices to settle and the topping to firm up.
Serve warm, optionally with a scoop of vanilla ice cream or a dollop of whipped cream for added indulgence.
