These simple mashed potatoes are silky-smooth and rich, no heavy cream required. To achieve this, we simmer the potatoes in milk, allowing them to absorb the dairy’s flavor while retaining their starch, as opposed to washing it away with boiling water. We tested the technique with russets but found their texture too mealy. Yukon Golds, on the other hand, had the perfect amount of starch, yielding buttery mashed potatoes with a naturally creamy texture.