Peel and cut the russet potatoes into evenly-sized chunks, then place them in a large pot. Cover with cold water and add a teaspoon of kosher salt. Bring to a boil, then simmer for 15-20 minutes until fork-tender.

While the potatoes boil, simmer the garlic cloves in a small saucepan filled with water for 2 minutes, then drain and set aside.

Drain the potatoes and return them to the pot. Off the heat, add the butter, warmed half and half, sour cream, and softened garlic. Mash until mostly smooth.

Season with kosher salt and black pepper to taste. Serve in a bowl and garnish with freshly chopped parsley if desired.