We are not thinkin' Arbys-- not after a roast beef sandich like this one. A classic creamy cheese sauce makes this sandwich super rich, while a horseradish sauce adds a kick. We love the onion bun, preferably bakery-made, but you could also use a pretzel bun instead. Make this sandwich the centerpiece of your Super Bowl Spread or serve along with beer and fries for a crowd-pleasing meal.