In a large pot or Dutch oven, add the sausage and cook stirring occasionally, until sausage is no longer pink, about 5 minutes. Transfer the cooked sausage to a paper towel lined plate. Set aside.
Add the onion, red pepper, and carrot to the pot and cook, stirring occasionally, until tender, about 5 minutes. Add the garlic and cook for 1 minute.
Add the chicken broth, tomatoes, bay leaf, salt, Italian seasoning, black pepper, and crushed red pepper flakes. Bring to a boil and add the tortellini.
Reduce the heat to a simmer and cook for 5 to 6 minutes or until tortellini is cooked through.
Add the sausage back to the pot and stir in the kale, Parmesan cheese, and basil.
If you are using the heavy cream, stir it in. If you aren’t using the cream, you might need to add 1 more cup of broth, depending on how thick you like your soup.
Remove the bay leaf. Ladle the soup into bowls and serve with additional Parmesan cheese, if desired.
