Mashed potatoes are the ultimate comfort food: Hot, creamy and full of carbs. To make them perfectly every time, try this: Melt the butter in your recipe and stir it in before adding the milk or cream. When the milk is mixed in first, it binds to the potatoes’ starch molecules and makes them gummy. But the fat in butter coats the starch and prevents the spuds from getting pasty. The result: a perfectly fluffy, smooth mash.