Heat a large pot over medium-high heat, adding the ground Italian sausage and diced yellow onion. Cook for about 8–10 minutes until sausage is browned and onions are translucent. Drain excess grease.

Stir in minced garlic and cook for an additional minute. Then sprinkle in the flour, stirring for 1-2 minutes to thicken the soup and remove raw flour taste.

Add the dried basil, oregano, cayenne pepper, hot sauce, mustard powder, and black pepper. Mix thoroughly and allow to toast for about a minute.

Pour in the chicken broth and deglaze the pot, then slowly stir in the heavy cream. Bring to a gentle boil, then reduce heat to let it simmer.

Add chopped kale and tortellini, simmer for 3-5 minutes until tortellini is tender. The tortellini should float to the top when done.

Taste and adjust seasoning if necessary, adding more salt or pepper as desired.

Ladle the soup into bowls and garnish with red pepper flakes if desired. Serve with garlic bread or biscuits.