Italian Sausage & Spinach Soup

1 lb. sweet Italian sausage 
8 to 9 cups chicken broth
1/2 medium onion, chopped 
1 cup of rice
1 large can chopped tomatoes 
6 oz baby spinach

Remove sausage from casing and sauté with onion over medium-high heat until cooked through, breaking the sausage apart as it cooks. Add chicken broth and heat until just boiling. Add tomatoes and rice; reduce heat, cover and simmer until rice is cooked, about 20 minutes (longer if using brown rice).  Add spinach and cook until spinach takes on a vibrant green color. Serve immediately. Garnish with your favorite shredded Italian cheese.