Cook bacon in a large skillet over medium heat until browned on both sides. Reserve 2 to 3 Tablespoons of the grease. Place cooked bacon on a paper towel–lined plate and allow to cool. Once cool enough to handle, chop into crumbles.

To the greased skillet, add the carrots, celery, and onion. Stir and cook until soft and tender, about 5 minutes. Add the garlic and stir and cook until fragrant, about 1 minute more. Remove from heat.

Place the creamed corn, corn, sweet potatoes, chicken, chicken broth, thyme, parsley, salt, and pepper into a 5-quart or larger slow cooker. Add the celery/carrot/onion mixture and the crumbled bacon (save some for garnish, if desired). Stir to combine and cover with the lid.

Cook on low heat for about 6–7 hours.

After 6–7 hours, whisk the warmed milk and cornstarch together. Pour into the soup. Give it a good stir, then cover.

Cook on low heat for 1 more hour.

Serve warm with a sprinkle of parsley, thyme, and/or any leftover bacon crumbles.

Leftovers keep well in the refrigerator for up to 1 week. To reheat, simply pour into a pot and cook over medium heat until warm. Soup freezes well for up to 3 months. Thaw and then reheat.