Heat olive oil in a large skillet over medium heat. Sauté diced onion until translucent, about 5.
Stir in minced garlic and cook for an additional minute.
Add ground beef or Italian sausage to the skillet and brown for 6-8 minutes.
Transfer meat mixture to the slow cooker. Add crushed tomatoes, tomato sauce, and beef broth.
Sprinkle in dried basil, dried oregano, salt, and black pepper. Stir until well combined.
Cover and cook on low for 360-480 or on high for 180-240.
About 30 minutes before serving, add broken lasagna noodles and stir into the soup.
Stir in ricotta cheese and half of the shredded mozzarella cheese until melted and creamy.
Before serving, sprinkle remaining mozzarella cheese and grated Parmesan cheese on top.
Garnish with fresh basil if desired and serve.