While loaves are baking, in 3-quart saucepan, place potatoes in generously salted cold water. Heat to boiling. Reduce heat; cook potatoes until fork-tender. Drain; return to saucepan. Add butter and 1/4 cup milk; mash until creamy and smooth, adding more milk as necessary. Season with salt and pepper. Make sure mashed potatoes are creamy and smooth so they can be piped onto meatloaves.