Spoon 1 cup spaghetti sauce into bottom of a 4-quart slow cooker. Mix remaining sauce with beef.
Place 2 uncooked lasagna noodles on top of sauce in slow cooker. Spread 1/3 of the meat mixture on top of noodles. Spread ¾ cup cottage cheese over meat. Sprinkle ½ cup mozzarella cheese over cottage cheese.
Add another layer of uncooked noodles, 1/3 meat mixture, the remaining cottage cheese and ½ cup mozzarella cheese.
Place another layer of uncooked noodles, meat mixture, and mozzarella cheese.
Sprinkle Parmesan cheese over top. Cook on low for 4 hours. (If cooked much longer, it gets a bit well done, Julie notes.)