Begin by peeling the Yukon Gold potatoes. You can use a vegetable peeler for this task. Once peeled, dice them into approximately 1-inch chunks. This size helps them cook evenly and quickly.
Place the diced potatoes into a large pot and fill it with enough water to cover them completely. I usually use cold water to start. This helps to cook the potatoes evenly.
Place the pot on medium-high heat and bring the water to a boil. Keep an eye on it, as it can boil over if you're not careful.
Once boiling, reduce the heat to a simmer. Let the potatoes cook uncovered for about 10 minutes, or until they can be easily pierced with a fork. You want them tender but not falling apart.
Once the potatoes are cooked, drain the water using a colander. Be cautious, as steam will escape when you pour out the water.
Immediately transfer the drained potatoes to the bowl of a stand mixer. If you don’t have a stand mixer, you can keep them in the pot and use a potato masher.
Mash the potatoes using a masher or the paddle attachment of the stand mixer on low speed. It is crucial to mash the potatoes while they are still hot to prevent them from becoming gummy.
Add the butter, sour cream, half of the milk, salt, and ground black pepper to the mashed potatoes. This is where the magic happens.
Switch the stand mixer to medium speed and whip the potatoes until they are just smooth. Gradually add the remaining milk as needed. Keep a close eye; you don’t want to overwhip them, as this can make them gluey.
If you're not serving immediately, cover the bowl with a lid or plastic wrap to keep the mashed potatoes warm. When ready to serve, garnish with chopped chives for that final touch.
