Cook and crumble sausage on the stovetop. Drain fat and add to your slow cooker.
Add onions, celery, carrots, garlic, salt, pepper, Italian seasoning, and chicken broth into your slow cooker. Cook on high 4-5 hours or on low for 7-7 hours.
In a small mixing bowl whisk together flour and half and half. Add to the slow cooker along with cheese tortellini. Allow to cook for 45 more minutes.
Add spinach in and cook for 5-10 more minutes. Last, slowly add in milk until you get the consistency you desire. Serve and enjoy!