Boil potatoes in salted water until very tender; about 20 minutes. Cut the florets off the broccoli and add to boiling potatoes, about 7 minutes. Drain and place back into pot.
Heat the milk, cream, and butter in a small saucepan. Pour sauce into the potatoes and broccoli, mash together. Season, to taste, with salt and pepper.
Recipe courtesy of The Neelys