Add the chopped potatoes, carrots, onion, corn, creamed corn, and crumbled turkey bacon to a slow cooker.
Pour in enough chicken broth or water to just cover the ingredients.
Add thyme, parsley, garlic powder, salt, and pepper, then stir to combine.
Cover and cook on high for about 5 hours or on low for 7–8 hours, until the vegetables are tender.
In a small bowl, whisk together the evaporated milk and cornstarch until smooth.
Stir the mixture into the slow cooker along with the butter, if using.
Cook for an additional 30 minutes, allowing the chowder to thicken.
Taste and adjust seasoning as needed.
Serve hot, making sure to scoop both the creamy broth and hearty ingredients.