This recipe is from the RSVP section in a February 1981 issue of Bon Appetit. It was requested from Stuart Anderson's Black Angus restaurant in Yakima, Washington. I made this for Easter dinner to go with our ham. I cooked and layered the pototoes in the casserole dish and made the sauce the night before and refrigerated both separately, covered, overnight. The next day, i warmed the sauce slightly and poured it over the potatoes and baked as instructed, increasing the baking time to 30 minutes. It came out perfect!