Add first 10 ingredients to your slow cooker. Cook on low 6-8 hours or high for 3-4 hours.
When fully cooked and potatoes are tender, prepare thickener. In a small measuring cup, add milk and cornstarch. Mix until smooth. Slowly stir thickener into soup. Continue to slowly stir until soup thickens.
If soup looks separated, use an emulsifier or food processor to blend the fats and create a creamy soup.
Serve with toppings!
For an even thicker soup, use a potato masher to mash some of the potatoes.