Warm the olive oil in a heavy pot over medium heat. Add the Italian sausage, breaking it up as it cooks, until it turns beautifully browned (about 3–5 minutes).

Toss in the diced onion and carrots. Sauté them in a mix of olive oil and a pat of butter for extra depth until softened, approximately 5 minutes.

Mix in the minced garlic, Italian seasoning, and fennel seeds and stir for about 1 minute until fragrant.

Sprinkle in the flour and whisk continuously for roughly 1 minute to achieve a light, toasted nutty aroma while forming a roux.

Pour in the chicken stock and add the Parmesan rind, if using. For an extra touch, splash a bit of white wine before the stock. Season with salt and pepper, then bring the mixture to a gentle boil. Lower the heat and simmer for 10 minutes, allowing the broth to thicken slightly.

Stir in the refrigerated tortellini and cook for an additional 4–5 minutes, until they are tender yet chewy.

Gently fold in the chopped spinach and slowly drizzle the heavy cream into the soup. Allow the spinach to wilt for 1–2 minutes before stirring in the fresh basil. Adjust salt and pepper to taste.

Ladle the soup into bowls and serve immediately with a side of crusty homemade bread if desired.