Begin by peeling the russet potatoes and cutting them into uniform chunks (about 1-2 inches) to ensure even cooking.
Place the potato chunks in a large pot, cover them with cold water, and add a generous pinch of salt. Bring to a boil over medium-high heat.
Once boiling, reduce the heat to medium and cook the potatoes for about 15-20 minutes, or until they are tender when pierced with a fork.
Drain the cooked potatoes in a colander and return them to the pot.
In a small saucepan, heat the milk and butter over low heat until the butter melts. Avoid boiling the mixture.
Using a potato masher or electric mixer, begin mashing the potatoes. Gradually add the milk and butter mixture while mashing to achieve your desired creaminess.
Continue to mash until the potatoes are smooth and fluffy. Season with salt and black pepper to taste. For added flavor, you can mix in garlic powder, sour cream, or cream cheese as desired.
Serve the mashed potatoes warm in a serving bowl, garnished with a pat of butter if desired.