Peel and dice the potatoes into 1-inch cubes. Place the diced potatoes in a colander and rinse well with cool water to remove the excess starch.
Place the rinsed potatoes in a pot and add fresh water until the potatoes are covered by one inch. Add ½ tsp salt to the water in the pot.
Place a lid on the pot and bring the water up to a boil. Boil the potatoes for 6-7 minutes, or until they are very tender (a fork can pierce the potato effortlessly).
Drain the potatoes in a colander and rinse again briefly with warm water.
While the potatoes are draining, add the butter and milk to the pot used to boil the potatoes. Heat them over medium until the butter has melted.
Add the drained potatoes back to the pot and mash with a potato masher.
Season the potatoes with salt and pepper (I used ½ tsp salt and ¼ tsp pepper, but if you use unsalted butter you'll probably want more salt).
For extra smooth and fluffy potatoes, use a hand mixer to whip the potatoes until there are no lumps and they are light and cloud-like. Serve and enjoy!