Start by heating a large skillet over medium-high heat. Add the ground beef and break it up as it cooks. Season with about 1½ teaspoons of Italian seasoning, plus a good pinch of salt and pepper. Cook until browned (a little pink is fine), then drain off any excess fat if needed.
Stir in the chopped onion and garlic and cook for a few more minutes, just until the onion softens and everything smells amazing. Transfer the mixture to your slow cooker.
Pour in the beef broth, pasta sauce, tomato paste, and the remaining Italian seasoning. Give it all a good stir so everything’s well combined.
Cover and cook on low for 4–5 hours or high for 2–3 hours. Since the beef is already cooked, you don’t need a super long cook time—but it can hang out on low a bit longer if needed.
About 30 minutes before serving, break the lasagna noodles into bite-sized pieces and stir them in. Cover again and cook until the noodles are tender.
When you’re ready to serve, ladle it into bowls and go in with the toppings—ricotta, mozzarella, parmesan, and a sprinkle of fresh herbs if you’ve got them. Finish with a little extra salt, pepper, or red pepper flakes to taste, and serve with garlic bread or crusty bread for dunking.