Cut peaches in half and remove pit. Heat grill pan or grill to high heat. Coat with olive oil spray. Place each peach half down on the grill and cook over high heat, undisturbed, for about 5 minutes or until grill marks appear.
Meanwhile, combine sour cream with brown sugar.
To serve, place grilled peach half, cut side up, on dish and top with a spoonful of sweetened sour cream. Serve immediately.