Use this foolproof mash to "frost" our Birthday Meatloaf Cake.
Put potatoes in large pan; cover with cold water by 1 inch. Add a pinch of salt. Bring to a boil. Reduce to a simmer; cook until tender, about 20 minutes. Drain. Press through food mill or ricer into pan.
Heat milk and cream in a small pan over medium-low heat. Pour over hot potatoes. Add butter; mash with potato masher. Stir in 2 teaspoons salt. Use immediately or refrigerate up to 3 days; reheat before using.