Creamy Tortellini Soup

Name: Creamy Tortellini Soup
Ingredients: 1 pound spicy Italian sausage, casing removed; 1 medium yellow onion (diced); 2 teaspoons Italian seasoning; 6 cloves garlic (finely chopped); Kosher salt and freshly ground black pepper, to taste; 2 tablespoons all-purpose flour; 4 cups chicken stock; 1 (8-ounce) can tomato sauce; 1 (9-ounce) package refrigerated three cheese tortellini; 1 bunch kale (stems removed and leaves chopped); 1/3 cup heavy cream; 1/3 cup parmesan cheese (plus more for garnish); 3 tablespoons fresh basil (chopped)