In a large pot or Dutch oven, brown the ground beef (or sausage) over medium heat until fully cooked. Drain excess fat if necessary.
Add the chopped onion and minced garlic to the pot, cooking until the onion becomes translucent, about 3-4 minutes.
Stir in the crushed tomatoes, beef broth, water, Italian seasoning, red pepper flakes (if using), salt, and pepper. Bring to a simmer.
Once simmering, add the broken lasagna noodles and cook according to package instructions, usually about 8-10 minutes, until al dente.
While the noodles are cooking, in a small bowl, combine ricotta cheese, half of the mozzarella, and half of the Parmesan. Mix well and season with a little salt and pepper.
Once the noodles are cooked, stir in the ricotta mixture into the soup, allowing it to melt slightly and blend in.
Serve the soup hot, distributing into bowls and topping with the remaining mozzarella and Parmesan cheese.
Garnish each bowl with fresh basil or parsley.
Notes
Feel free to customize with your favorite vegetables or proteins.