1
Adjust racks to top and middle positions and preheat oven to 425 degrees. Wash and dry produce.
Dice potatoes into ½-inch pieces. Place in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes. Reserve ½ cup potato cooking liquid, then drain.
Return potatoes to pot and mash until smooth and creamy, adding splashes of reserved potato cooking liquid as needed. Cover to keep warm. (You’ll finish the potatoes in Step 6.)