To a large pot or dutch oven, add ground sausage and cook over medium heat until browned. Remove the meat from pot and set aside leaving behind about a tbsp of oil.
Add 2 tbsp butter to the pot. Once melted, add the chopped onion, mushrooms, and a few pinches of salt and pepper. Cook until onions have softened and mushrooms are golden brown or for 4-5 minutes. Add in minced garlic and cook for another minute. Sprinkle flour over veggies, stir well to combine and cook for 1 more minute.
Pour in the chicken broth and bring to a boil. Reduce heat to medium low and let soup simmer for 5 minutes.
Add in the broken lasagna noodles, italian seasoning, crushed red pepper, salt and pepper. Bring to a low boil and cook for 12-15 minutes or until noodles are al dente.
Add cream, stir until well combined then turn off heat. Add spinach and parmesan, stir until spinach is wilted.