Place the diced potatoes and chopped onion in the slow cooker.
Pour the chicken broth over the potatoes and onions.
Spoon the cream of chicken soup on top without stirring.
Cover and cook on LOW for 6-7 hours or HIGH for 3-4 hours until potatoes are tender.
Stir in the milk and season with salt and pepper. Mash some potatoes if a thicker texture is desired.
Ladle into bowls and serve with optional toppings like shredded cheese, bacon bits, and green onions.
Notes
For extra creaminess, use half-and-half instead of milk. Stir in shredded cheddar during the last 15 minutes for a cheesy variation. Mash some potatoes for a thicker texture.