In a large stockpot or dutch oven (at least 6 quarts), brown 1 pound bulk Italian sausage over medium heat.
Add the 1 small diced onion, 1 teaspoon garlic powder, and ½ teaspoon dried oregano. Cook, stirring frequently, until the onions are translucent.
Stir in the 28 ounces canned crushed tomatoes and 8 cups chicken stock. Turn heat up to medium-high and bring to a boil.
Stir in the 16 ounces ditalini pasta and boil for 8 minutes or until just shy of al dente.
Stir the 2 Tablespoons cornstarch into 1½ cups whole milk to make a slurry. Pour into the soup, stir until it comes back to a boil.
Drop heat to low and stir in the 10 ounces chopped spinach and ¾ cup grated parmesan cheese. Allow the spinach to wilt and the cheese to melt into the soup.
Serve with additional parmesan cheese if desired.
Notes
If you can't find bulk Italian sausage, buy links and remove the casings.
For more spice, use hot Italian sausage or add a pinch of red pepper flakes.
For more fiber, double the spinach or add a can of white beans.
My family likes hearty soups with lots of chunks. Feel free to use less pasta if you like a higher broth to stuff ratio.