The King is back with a new burger, the Mushroom & Swiss Steakhouse. Premium burgers have been making noise at fast food joints for some time now, and the King has taken some time off from reverse pickpocketing to launch this new product. It features flame grilled Angus Beef, crispy onions and A1 steak sauce on a golden, corn dusted bun. Then it all comes together with the classic tandem of mushrooms and Swiss cheese. Departing from traditional burger shape, these are served on an oval bun with an oversized patty to match. If you wanna take a break from that trademark Whopper, get your hands on one of these beasts. Clocks in at 840 calories, 48 g fat and 40 g protein. Available for a limited time at BK for $3.50.