If making ahead to bake and serve at a later date: Line 13x9-inch (3-quart) baking dish with 2 layers of plastic wrap, leaving enough overhang to completely enclose assembled casserole. Allow sauce mixture to cool completely, covered, 30 to 45 minutes in refrigerator before assembling casserole. Assemble casserole in dish; cover with another layer of plastic wrap. Freeze unbaked casserole about 8 hours or until completely frozen. Transfer frozen casserole to labeled 2-gallon resealable freezer plastic bag. Remove air; seal and freeze up to three months. To bake: Spray 13x9-inch (3-quart) baking dish with cooking spray. Remove plastic wrap from casserole; place in baking dish. Cover tightly with foil; thaw completely in refrigerator, 24 to 48 hours. Heat oven to 350°F. Uncover; bake 45 to 55 minutes or until hot and bubbly on edges (165°F in center). Let stand 20 minutes before serving. Serve with Toppings, as desired.