Place potatoes on a foil-lined rimmed baking sheet. In a small bowl, mash butter, shallot and zest; season generously with salt and very generously with pepper. Brush some lemon-pepper butter on the potatoes. Roast at 425 degrees , 30 minutes; brush with more lemon-pepper butter. Roast until tender, about 30 minutes more. Drizzle the potatoes with lemon juice. Broil until browned, 1 to 3 minutes. Season; brush with remaining lemon-pepper butter.