Tortellini Soup with Spinach and Kielbasa

Adapted from

2 tablespoons olive oil
1 12-ounce fully cooked smoked kielbasa sausage, thinly sliced
1 medium onion, chopped
1 cup chopped fresh fennel (do not omit!)
4 garlic cloves, minced
1 ½  teaspoons chopped fresh thyme
1/4 teaspoon dried crushed red pepper
10 cups low sodium chicken stock
4 cups of baby spinach
1 15-ounce can cannellini beans, rinsed and drained
1 9-ounces package cheese tortellini
1 cup grated Parmesan cheese

Heat oil in a heavy large pot over medium-high heat. Add next six ingredients, sauté until vegetables are soft and Kielbasa is brown, about 12 minutes. Stir in stock and bring to a boil. Stir in cannellini beans, reduce heat to low and simmer about four minutes. Stir in spinach and allow to wilt. Add tortellini to the soup and simmer until pasta is tender, but still firm, about five minutes. Serve topped with grated Parmesan.