In a skillet over medium-high heat add vegetable oil and sauté carrots, celery, and onions until tender, about 5 minutes. Transfer to 6qt crockpot and add potatoes, chicken stock, garlic powder, thyme, paprika, bay leaf, salt, and pepper. Cover and cook on high for 4-5 hours or low for 6-7 hours.
In a small bowl combine cornstarch and water to make a slurry. To the crockpot stir in corn, milk, and the cornstarch slurry. Stir and cook one more hour on high.
Using a potato masher, mash potatoes and vegetables to thicken soup (you can mash as much or as little as desired). Top with crumbled bacon and chopped chives.
Notes
Leftovers will keep in an airtight container in the refrigerator for 4 days.