Heat the olive oil in a large pot over medium-high heat. Add the ground beef, breaking it apart with a wooden spoon. Cook until browned and no longer pink, about 5-7 minutes. Drain any excess fat and set the beef aside.
In the same pot, add the chopped onion and bell pepper. Sauté for 4-5 minutes until softened and fragrant. Stir in the minced garlic and cook for another minute, being careful not to burn it.
Return the browned beef to the pot. Add the crushed tomatoes, beef broth, oregano, basil, red pepper flakes, salt, and pepper. Stir to combine everything well. Bring the soup to a gentle boil, then reduce heat and simmer for 15 minutes to let the flavors meld.
Drop the broken lasagna noodles into the simmering soup. Cook uncovered until the noodles are tender, about 10-12 minutes. Stir occasionally to prevent sticking.
Turn off the heat. Ladle the soup into bowls and add generous dollops of ricotta cheese on top. Sprinkle with grated Parmesan and garnish with fresh basil leaves.
Serve the soup hot with crusty bread or a simple salad.
