Divide ground chuck into 8 equal portions and shape into patties, keeping each quite thin. Sear briskly on lightly greased hot grill or griddle, turning only once, till medium well. Arrange each patty on bottom half of hamburger buns. Apply 2 or 3 tablespoons of Big Buy Hamburger Sauce to each patty and then arrange a little shredded lettuce over each. Place one atop the other and a slice of American cheese over the top patty. Apply top of hamburger bun and serve at once. Makes 4 double-deckers. BIG BUY HAMBURGER SAUCE: Stir all ingredients together with fork. Refrigerate in covered container to use within 2 weeks. Makes about 2 cups. (Recipe may be divided in half.)