Combine all ingredients in a large bowl and mix well.
To freeze: Divide into four ziptop freezer bags and seal tightly. Freeze flat.
To serve: Thaw overnight (or for 8 hours) in the refrigerator. Dump into a greased casserole dish (each bag will fill an 8×8-inch pan; two bags will fill a 9×13-inch pan). Sprinkle with additional shredded cheese, if desired.
Bake at 350 degrees for 25-30 minutes, or until heated through and bubbly.