1. Place potatoes in a large saucepan; cover with water. Bring to a boil; reduce heat, and simmer 15 minutes or until tender. Drain. Press potatoes through a ricer back into pan, or mash with a potato masher to desired consistency.
2. Add half-and-half, 1 tablespoon melted butter, kosher salt, and black pepper; stir well. Melt 1 tablespoon butter in a medium skillet over medium heat. Add leek; cook 4 minutes or until tender, stirring frequently. Stir into potatoes.