Heat olive oil in a large pot over medium heat. Brown Italian sausage, breaking it up, about 7-8 minutes. Remove with slotted spoon.
In same pot, sauté diced onion until soft, 5 minutes. Add minced garlic, cook 1 minute.
Add chicken broth, scrape bits. Bring to boil, simmer. Stir in heavy cream, oregano, basil, red pepper flakes, salt, pepper.
Add ditalini pasta, simmer until al dente, 8 minutes.
Return sausage, add spinach, wilt 2 minutes.
Off heat, stir in Parmesan until melted. Garnish with parsley.