Heat olive oil in a large pot over medium heat. Add sausage and cook until browned, breaking it up as it cooks.
Add onion and cook until softened, about 3–4 minutes. Stir in garlic and tomato paste and cook for 1 minute.
Add oregano, basil, red pepper flakes, salt, and pepper. Pour in crushed tomatoes and broth. Bring to a simmer.
Add lasagna noodles and cook, stirring occasionally, until noodles are tender, about 10–12 minutes.
In a small bowl, combine ricotta, mozzarella, and Parmesan. Season lightly with salt and pepper.
Serve soup hot with a spoonful of the cheese mixture on top and garnish with fresh herbs if desired.
