Cook the Meat: In a large Dutch oven, heat olive oil over medium heat. Add sausage and cook for 5-7 minutes until browned, breaking it up with a spoon. Remove excess fat, leaving 1 tbsp.
Sauté Aromatics: Add onion and cook for 3-4 minutes until softened. Stir in garlic, Italian seasoning, and red pepper flakes; sauté for 30 seconds.
Build the Base: Sprinkle flour over the mixture and stir for 1 minute. Pour in broth and tomatoes, scraping the pot. Bring to a simmer.
Cook Pasta: Add broken lasagna noodles and simmer for 10-12 minutes until al dente, stirring occasionally.
Make It Creamy: Reduce heat to low. Stir in cream and Parmesan until smooth. Season with salt and pepper.
Serve: Ladle into bowls. Top with mozzarella, a dollop of ricotta (if using), and parsley or basil. Serve with crusty bread.