Add olive oil to a 4-5 quart saute pan over medium high heat. Add onions and sausage and cook until lightly browned. Add garlic and cook for about 30 seconds.

Add chicken broth, tomatoes, milk (or heavy cream), pasta, and seasonings. Bring the mixture to a boil, cover, and reduce heat to low. Simmer for about 15 minutes, or until pasta is tender.

Turn off the heat and stir in 1/2 cup of cheese. Sprinkle remaining cheese on top and cover for about five minutes to allow cheese to melt. Top with sliced scallions and serve.