Pour off grease from pan, return to stove, and add olive oil. Add onion, garlic, kale, and crushed red pepper. Cook for two or three minutes, stirring, until onion has softened and kale is slightly wilted. Add chicken broth, crushed tomatoes, and Italian seasoning. Set stove to medium-high and bring mixture just to a boil then reduce heat to low, cover, and simmer for 20 minutes. Remove cover and stir in tortellini and cooked sausage. Increase heat and bring to a boil then reduce heat, cover and simmer for an additional 10 minutes or until tortellini is tender. Remove cover stir in Parmesan. Taste and season with additional salt and fresh ground pepper, as desired.