Gather all your ingredients to make the cooking process smoother.
Heat olive oil in a large pot over medium heat. Sauté diced onion for 3-4 minutes until soft, then add minced garlic and cook for an additional minute.
Add ground Italian sausage to the pot, breaking it apart and cooking until browned (5-7 minutes). Stir in Italian seasoning and red pepper flakes, then add chicken broth and diced tomatoes. Bring to a boil, add lasagna noodles, reduce heat, and simmer for 10-12 minutes until noodles are tender.
Stir in heavy cream and grated Parmesan cheese until well combined. Add fresh spinach and cook for an additional 2-3 minutes until wilted. Season with salt and pepper to taste.
Let the soup simmer for a few more minutes to meld flavors. Serve in bowls garnished with fresh basil.