Heat a large, heavy bottomed pan over medium-high heat. Heat vegetable oil and add diced onion. Saute until onions are soft.
Crumble Italian Sausage and garlic with the onion. Cook until sausage is no longer pink.
Stir in crushed tomatoes, vegetable (or chicken) broth, basil, salt and pepper. Bring to a boil, reduce heat to low, and cover. Let soup simmer for 20-30 minutes.
Add tortellini and spinach and simmer for about ten minutes, until pasta is tender.
Serve with shredded Parmesan.
Crostini
Slice baguette into 1/2 inch thick slices. Butter one side and place butter side down in a hot skillet until golden brown. Flip bread slices over and sprinkle with Parmesan while the other side gets golden brown. Transfer to a plate and immediately cover loosely with foil if cheese has not completely melted.