This recipe is perfect for freezing! Once you've assembled the shells in the baking dish, cover it tightly with foil and place it in the freezer. To thaw, move the dish to the refrigerator about 10 hours before you plan to serve, such as in the morning for a dinner preparation. Before baking, allow the dish to sit at room temperature while the oven preheats. Bake, covered, for 30 minutes, or until the shells are fully thawed and heated through.