Heat oven to 375°. Spray bottom and sides of square baking dish (8x8x2 inches) or rectangular baking dish (11x7x11/2 inches) with cooking spray.
Place peaches and blueberries in baking dish. Mix brown sugar, orange juice, cinnamon and nutmeg in small bowl; drizzle over fruit.
Bake for 15 minutes. Sprinkle with crushed cereal and walnuts. Bake 10 to 15 minutes longer or until peaches are tender when pierced with a fork. Serve warm or cold.