Start by placing the potato chunks into a large pot and covering them with cold water. This step ensures even cooking and prevents the potatoes from becoming gummy. Turn on the heat and bring the water to a boil.
Once boiling, reduce the heat to a simmer. Partially cover the pot and let the potatoes cook for about 15 to 18 minutes, or until they can be easily pierced with a fork. Keep an eye on them; you want them tender but not mushy.
Meanwhile, in a small saucepan, heat the whole milk together with the smashed garlic cloves over medium heat. Stir occasionally until the milk is just steaming, then remove it from the heat and set it aside. The idea here is to infuse the milk with garlic flavor.
Once the potatoes are cooked, drain them in a colander, but return them to the pot. Place the pot back on low heat. This helps evaporate any excess moisture, ensuring your mash is perfectly creamy.
Using a potato masher or an electric hand mixer, start mashing the potatoes until they reach your desired texture. Remember, it's best to mash them while they’re hot to avoid a gummy consistency.
Drizzle the hot garlic-infused milk into the potatoes while you mash. This will help create a smooth texture. Add in the unsalted butter by cutting it into small chunks and mixing it in until it melts and blends seamlessly.
Next, incorporate the sour cream into the mix, stirring until well combined. This adds creaminess and a hint of tang that complements the other flavors beautifully.
Season with fine sea salt to taste. Start with 1 to 1.5 teaspoons, and adjust based on your preference.
Finally, serve the mashed potatoes warm. Drizzle more melted butter on top if desired and garnish with finely chopped chives for a pop of color and freshness.