Pour chicken stock, cubed potatoes, carrots, and onions in a 2-quart pot. (Instead of chicken stock, I use 6 cups of water and 3-5 TBS of chicken bouillon.) Set to High.
Add the bay leaf, salt and pepper, and the half stick of butter. Stir ingredients. Bring to a boil.
When veggies are tender, reduce heat to low. Pour milk and heat thoroughly. (Note: Don't overheat, milk will curdle!) Serve immediately. (This soup works well as a left-over. Heat in microwave for 3-5 minutes).