Preheat oven to 375 F.
Mix first 4 ingredients in large bowl, stir in 3/4 cup cheddar and 1/2 cup cracker crumbs.
Spoon into 2L casserole dish sprayed with cooking spray, top with remaining cracker crumbs and cheese.
Bake 20-25 minutes or until crumb topping is golden brown and cheese is melted.