Yes! You can fully assemble this dish up to 12 hours before you bake it. Cover the pan with an oven safe lid or with aluminum foil that's been lightly sprayed with non-stick spray (to keep the cheese from sticking to it) and keep it in the refrigerator. When ready to bake, simply pull the pan from the refrigerator and pop it directly in a preheated oven. The shells will require about 10 additional minutes of baking time if they've been in the refrigerator for a few hours.