**Cook the Beef**
- In a large skillet over medium heat, cook the ground beef until browned, breaking it into crumbles. Drain excess fat, if needed. Add onion and garlic and cook until softened, about 3 minutes. Transfer the mixture to the slow cooker.
**Prepare the Soup Base**
- Add broth, crushed tomatoes, diced tomatoes, tomato paste, basil, oregano, red pepper flakes, salt, and pepper to the slow cooker. Stir to combine.
**Cook in the Slow Cooker**
- Cover and cook on low for 6–7 hours or on high for 3–4 hours.
**Add the Noodles**
- About 20–30 minutes before serving, stir in the broken lasagna noodles. Cover and cook until the noodles are tender.
**Finish with Cheese**
- Stir in mozzarella and Parmesan cheese until melted and well combined.
**Serve**
- Ladle the soup into bowls and top each serving with a spoonful of ricotta cheese. Garnish with fresh parsley and serve with crusty bread or a side salad.