1Heat oven to 375°F. Spray 13x9-inch (3-quart) glass baking dish with cooking spray. Place peaches in dish. Sprinkle sugar, cornstarch, cinnamon, and lemon juice over peaches; mix lightly with spoon until coated. Dot top with 3 tablespoons butter.
2In large bowl, mix topping ingredients with spoon until soft dough forms.
3With hands, shape golf ball-sized balls of dough into 1/4-inch-thick disks. Place disks over peaches, covering most of the top. (With any remaining dough, make and bake cookies.)
4Bake 25 to 30 minutes or until topping is golden brown. Cool 10 to 15 minutes before serving.