Wash and peel the Yukon Gold potatoes, then cut them into 1-inch cubes. Place in a large pot and cover with cold water. Add 1 tablespoon of kosher salt and bring to a boil. Reduce heat and simmer for 15-20 minutes until fork-tender, then drain and return to pot.

In a small saucepan, combine ½ cup of heavy cream and 4 tablespoons of unsalted butter over medium-low heat until melted. Stir occasionally, then add 2 crushed garlic cloves and 2 sprigs of fresh rosemary. Steep for about 10 minutes, then remove rosemary and mash garlic if desired.

Mash the drained potatoes in the pot for 1-2 minutes until smooth and fluffy. Use a ricer for silkier potatoes.

Pour the warm cream and garlic mixture into the mashed potatoes, mixing gently until fully combined. Adjust the consistency by adding more cream or butter if needed. Season to taste with additional kosher salt and freshly cracked black pepper.

Transfer the mashed potatoes to a serving dish, garnish with extra sprigs of rosemary and a pat of butter, and serve hot.