Preheat oven to 375°.
Make peaches: In a large bowl, combine peaches, sugar, lemon juice, cinnamon, corn starch, and salt.
Make topping: In the bowl of your KitchenAid stand mixer combine flour, brown sugar, salt, and cinnamon. Pour in melted butter and stir until mixture resembles coarse crumbs.
Pour peaches and juices into a 2 qt. baking dish (such as 11"x7"). Sprinkle crumb topping evenly over peaches.
Bake until topping is golden and peaches are bubbling, 45 to 50 minutes.
Serve warm with ice cream, if desired.
