To freeze: Before adding your ingredients, line your baking pan/dish with a single sheet of parchment paper (leaving enough paper to hang over the sides). When your pan is ready, pop it in the freezer for about 1-2 hours until the ingredients are solid. Remove the pan and lift sides of the parchment paper, pulling out the entire casserole. Transfer the casserole to a separate container and return it to the freezer. Don’t forget to label the container and include the date!