Make-Ahead Tip: Prepare this casserole the night before! Assemble everything in the baking dish, cover tightly with plastic wrap, and refrigerate overnight. In the morning, simply bake as directed. Storage: Store leftovers in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave. Variations: For a citrus twist, add the zest of one orange to the egg mixture. You can also substitute the packaged frosting with a homemade cream cheese glaze or a simple vanilla buttercream.