4 pounds russet potatoes, peeled and cubed
3 Tbsp. Kosher salt
1 sprig of rosemary
2 bay leaves
ground black pepper
1 cup whole milk
1/2 cup heavy whipping cream
1 stick butter, chilled and cubed
In a big pot, fill up halfway with water. Place potatoes in and then add more water, covering over 1 inch. Boil for 25 minutes. Drain potatoes and let rest for 20-30 minutes. This step is important.
Meanwhile, heat milk, cream, rosemary, bay leaves, and pepper in a saucepan until mixture is very hot but not boiling (about 10 minutes). Remove from heat and let mixture infuse for 20 minutes; strain. This will add herbal flavor without coloring the liquid.
Mix the potatoes and butter together in a large mixing bowl. Stir in the hot cream mixture. Season generously to taste with kosher salt and freshly ground black pepper.