Melt butter in your slow cooker on the sauté setting for 1-2 minutes until bubbly. Stir in flour until mixture reaches a smooth paste, cooking for an additional 1-2 minutes to create a roux.

Add diced onion and chopped white button mushrooms to the roux, stirring for about 3-4 minutes. Incorporate thyme, basil, oregano, and garlic, stir for another minute.

Pour in chicken broth and add shredded cooked chicken. Season generously with red chili flakes, salt, and pepper to taste, and stir well.

Cover the slow cooker and set it to low for 6-8 hours or high for 4-5 hours.

About 30 minutes before serving, add broken lasagna noodles and spinach to the soup, stirring gently until noodles are submerged.

Once noodles are tender, stir in cream and cheese blend until melted and creamy. Adjust thickness with more broth if needed.

Ladle the soup into bowls and garnish with additional cheese or crispy prosciutto if desired.