Add all of the soup base ingredients to the crockpot. Cover and cook on high for 3-4 hours.
About 30 minutes before the soup is ready, use an immersion blender to blend until smooth.
During this last 30 minutes you'll also want to make your roux. Add butter to a pot over medium heat. Whisk in the flour and then slowly add the heavy cream and evaporated milk. Continue whisking until smooth. Add the parmesan cheese and stir until melted.
Add the roux to the crockpot and stir to combine.
Serve and enjoy!