Prepare the peach filling: In a large bowl, combine sliced peaches, sugar, cornstarch, cinnamon, and lemon juice. Mix gently until well coated. Transfer to a greased baking dish.
Make the topping: In another bowl, mix flour, oats, brown sugar, cinnamon, and salt. Cut in cold butter using a pastry cutter or fingers until crumbly.
Assemble: Sprinkle the topping evenly over the peaches.
Bake: Bake for 35 minutes or until the topping is golden and the filling is bubbling.
Cool: Let it rest for 10 minutes before serving. Serve warm with vanilla ice cream if desired.
Notes
You can use frozen peaches if fresh aren’t available—just thaw and drain them first. This crisp also works great with a mix of peaches and berries for added flavor.