Heat a large pot over medium heat and brown the ground sausage. Just before the sausage is fully cooked, add the diced onion, cooking for 2–3 minutes until translucent. Then, stir in the garlic and cook for an additional 1–2 minutes.

Sprinkle the all-purpose flour over the sausage mixture and cook for 2 minutes, stirring constantly. Add the Italian seasoning, mustard powder, and a pinch of red pepper for a little heat (if desired), and cook for 1 more minute.

Gradually pour in the chicken broth, using a spatula or spoon to gently scrape the bottom of the pot to deglaze and incorporate all the flavor.

Stir in the heavy cream and bring the mixture to a gentle boil.

Add the chopped spinach and frozen tortellini, cooking for 3–4 minutes or until the tortellini is tender and cooked through.

Taste the soup and adjust the seasoning with salt and pepper as needed.

Serve hot and enjoy a comforting, hearty bowl of this delicious Italian Sausage Tortellini Soup!