4 lb large yellow-fleshed potatoes such as Yukon Gold, peeled and quartered
1 3/4 cups half-and-half
3/4 stick (6 tablespoons) unsalted butter, cut into tablespoon pieces
1 1/2 teaspoons of fine sea salt
1/2 teaspoon fresh ground black pepper
1/8 cup Spicy Horseradish from Hawkshead
3 tablespoons of Porcini Oil