Add canned tomatoes (do not drain), diced tomato, diced onions, and minced garlic to the slow cooker. Pour in flour mixture, chicken broth, tomato paste, butter, 1 cup heavy whipping cream, and garlic powder. Stir to combine. Cover and set the slow cooker to high and cook for 3 hours, or low for 5 hours.
Use an immersion blender to blend the soup or place the soup in a blender in batches in a stand blender (be sure lid is on well).
Top with shredded parmesan and fresh basil. Swirl ¼ cup of heavy whipping cream into the soup. Enjoy!
If you want sausage, brown and crumble it. Stir into the finished soup.
Notes
Can I use a different broth?You can use 5 cups of vegetable broth in substitution for the chicken broth. They are both similar in flavor.Does this soup freeze well?It sure does! You can make several batches and freeze them in an airtight container or freezer bags to quickly grab for a quick meal. If you choose to keep the leftovers in the refrigerator, they will keep for about three days.Can I cook this on the stove top?Yes! Everything can go according to the recipe; however, be sure to use a big pot and set the heating on simmer for about an hour before blending (stirring often); you may need to add additional broth.Variations:
Tomato Basil - There are many variations of this soup, with the most popular being tomato basil soup. Everything is pretty much the same, except a nice helping of fresh basil is added toward the beginning and cooked with the rest of the ingredients.
Chicken - Another variation adds chicken. Add two small chicken breasts to the slow cooker at the beginning of the cooking time. Before blending remove and shred. Blend the soup, then stir in the shredded chicken.
Veggie Packed - Add more herbs and vegetables. Celery, carrots, thyme, and oregano are a few additions that pair perfectly with this soup; no one will even know you snuck in extra vegetables after pulverizing.