COOK THE POTATOES: Place the peeled potatoes in a large pot and cover completely with water. Add 2 teaspoons of the salt and bring to a boil over medium-high heat. Cook until the potatoes are tender; drain and return to the pot.

BROWN THE BUTTER: While the potatoes are cooking, place the butter in a saucepan and melt, stirring constantly. Continue to cook until the butter turns a golden brown color. It may start to foam or pop - keep stirring or swirling the pan to make sure the butter does not burn. It will take about 6-8 minutes for the butter to turn a deep brown and for it to smell nutty. As soon as it is done, immediately remove from the heat and pour into a bowl to stop the cooking.

MASH THE POTATOES: Use a masher to start mashing the potatoes in the pot. Add the buttermilk, milk, remaining teaspoon of salt and the pepper. Reserve about 2 tablespoons of the browned butter and add the rest to the pot. Mash the potatoes until you reach your desired consistency.

SERVE: Transfer the potatoes to a serving dish and drizzle with the reserved brown butter. Serve warm.