Once a year, what chain benefits the Help a London Child charity by selling a $200 hamburger made with Wagyu beef, white truffles, Pata Negra ham slices, Cristal onion straws, Modena balsamic vinegar, lambs lettuce, pink Himalayan rock salt, organic white wine and shallot-infused mayonnaise, on an Iranian saffron and white truffle dusted bun?