Pre-heat oven to 350 F, placing rack in the middle of the oven.
Spray an 8x8 inch baking pan lightly with cooking spray. Arrange peach halves in prepared pan and set aside.
In a medium bowl, add oats, flour, brown sugar and cinnamon. Stir to combine. Add the melted butter and blend mixture until it appears crumbly. Divide the crumb mixture evenly and place on top of peach halves.
Bake the peaches 35-40 minutes or until the crumb topping is golden brown. Serve warm with ice cream if desired.