Do not substitute no-boil lasagna noodles for the traditional, curly-edged lasagna noodles here. Meatloaf mix is a combination of ground beef, pork, and veal, sold pre-packaged in many supermarkets. If it’s unavailable, use ½ pound each ground pork and 85 percent ground beef. We recommend using either whole milk or part-skim ricotta here, but do not use fat-free ricotta, which has a very dry texture and bland flavor.