Preheat oven to 350 degrees.

In a bowl, combine the mayonnaise, dried onion, poppy seeds, mustard, and Worcestershire to create the secret sandwich sauce.

To make the sandwiches, spread some of the sauce on the bottom of the buns, then top with roast beef. Spread cheese whiz on the top of the buns and place the top on the roast beef.

Wrap the sandwiches in foil. Place sandwiches in a 350 degree oven for 15 to 20 minutes until heated through. Serves 8.