To prepare in advance, complete all steps up to the assembly and store the topping separately. Freeze the casserole, wrapped in plastic and foil, for up to 2 months. For reheating, thaw overnight in the refrigerator. If prebaked, heat uncovered at 350°F for 20 minutes; if unbaked, follow the standard baking instructions.
Optional Add-ins: For savory variations, consider including crumbled bacon, sausage, ham, cheese, green chilies, or chorizo. For a sweeter profile, incorporate sliced apples, blueberries, chopped pecans, pineapple chunks, orange zest, or apricots.