In a large pot over medium heat, melt the butter and sauté the onions, carrots, celery, and garlic until softened.
Sprinkle in the flour and stir for about one minute to cook out the raw taste.
Slowly pour in the chicken stock, stirring continuously to combine.
Add the milk and heavy cream, then season with salt, pepper, Italian seasoning, smoked paprika, garlic powder, onion powder, and crushed red pepper flakes.
Bring the mixture to a simmer, then add the shredded rotisserie chicken and gnocchi.
Cook for about 5 minutes or until the gnocchi is tender and floats to the top.
Stir in the fresh spinach and let it wilt into the soup.
Taste and adjust seasoning if needed.
Serve hot, topped with mozzarella cheese and a side of warm breadsticks.