A simple slow cooker lasagna recipe uses uncooked lasagna noodles, 1 to 2 pounds of crumbled cooked hamburger, one to two jars of spaghetti or marinara sauce, 2 cups of cottage or ricotta cheese, and 3 cups of shredded mozzarella and grated Parmesan cheese. Cook on low for 3 hours.
Combine all but 1 cup of sauce with cooked hamburger, and simmer for 20 minutes. Spread the rest of the sauce on the bottom of the cooker. Make 3 layers beginning with lasagna noodles, followed by a third of the meat mixture, ricotta or cottage cheese, and shredded mozzarella. Repeat the layers twice more, and grate Parmesan cheese on top.
To make tomato sauce from scratch brown hamburger and a chopped onion until thoroughly cooked, then drain. Add a 29-ounce can of tomato sauce, 6-ounce can of tomato paste and 1 cup of water, then season it to taste with dried basil, oregano, thyme, parsley and salt. Simmer for about 30 minutes before utilizing the lasagna layers.
A beaten egg helps the ricotta spread more evenly, and for extra flavor, add either fresh baby spinach, or thawed and drained, frozen, chopped spinach. Experiment with the wide variety of lasagna noodles available, such as those made with whole wheat or gluten-free rice.