Peel potatoes and cut in half or in quarters, if potatoes are very large. Add to a large pot and cover completely until there is an inch of water above the tops of the potatoes. Add a generous tablespoon of salt to the water. Add garlic to the water, if using.
4-5 pounds potatoes, 1 1/2 teaspoons table salt, 4-6 cloves garlic
Bring the water to a boil over high heat, then reduce the heat to a medium to let the potatoes simmer until cooked through (usually about 15 to 20 minutes, depending on the size of the potatoes). Cook just until the potatoes are tender enough to be pierced with a fork or sharp knife. Drain well.
Heat milk in the microwave for 60 seconds while the potatoes are draining and set aside.
1 cup whole milk
In the same pot you cooked the potatoes in, mash the potatoes by hand using a potato masher, potato ricer, or an electric mixer just enough to break them up.
Add the warm milk slowly while mixing or mashing. Do not overmix! Mix in remaining 1 1/2 teaspoons salt.
Add the softened butter, a few tablespoons at a time, mixing on low speed or mashing with the potato masher after each addition. Add cream cheese, if using. Taste and adjust salt, if needed.
1/2 cup salted butter, 4 ounces cream cheese
Transfer the finished mashed potatoes to a serving bowl and garnish with fresh chopped parsley, cracked pepper, or chives. Serve warm.
1 Tablespoon fresh parsley or chives, Fresh cracked black pepper