Peel potatoes. Dice into approximately 2 inch cubes.
Put potatoes into large pot. Fill with enough water to cover potatoes.
Stir in salt. (when cooking is an appropriate time to add salt as it helps flavor the potatoes even more)
Place pot over high heat and bring to a boil. Cook potatoes until fork tender, about 15 minutes. They will cook faster covered, but watch out for the starchy water from the potatoes bubbling up and boiling over. As they start boiling I turn the heat down a bit and tilt the cover on top. This reduces the chance of boil over and the need to clean up even more mess. However, you can also try putting a wooden spoon across the top of the uncovered pot.
Drain water from potatoes. I usually tilt the lid slightly and drain the water out while keeping the potatoes in. Some people might want to use a colander. Use the method that works easiest for you.
Once drained, add salt and pepper. I would start with ¼ tsp. of each, but you should adjust to your taste. Then add the milk and chicken stock.
Using a masher, mash the potatoes to desired smoothness. Some people like potato chunks yet, I like them pretty creamy.
If you find that the potatoes are a little dry, you can add more liquid – either more milk or stock.