In a large skillet over medium heat, add the Italian sausage and chopped onions. Brown for about 7-8 minutes, then add minced garlic and cook for an additional 30 seconds.

Transfer the sausage and onion mixture to your Crockpot, scraping any bits from the skillet.

Add chopped carrots, chopped celery, crushed tomatoes, diced tomatoes with juices, and chicken broth to the Crockpot. Stir well.

Cover and set the Crockpot to cook on low for 6-8 hours or on high for 3-4 hours.

Around 30 minutes before serving, stir in cheese tortellini, fresh spinach, and heavy cream if using. Set to high to heat through.

Before serving, taste and adjust seasoning with salt and pepper. Ladle into bowls and enjoy.