Mix Together The Ground Beef, Onion, Mushrooms, Garlic, Egg White, And Seasoned Salt In A Bowl. Form Six Equal-Sized Hamburger Patties From The Mixture. Season Burgers On Each Side With Salt And Pepper. Heat A Large Skillet Over Medium-High Heat. Lie The Patties Into The Skillet And Cook Until Golden Brown, About 3 Minutes Per Side. Top Each With A Slice Of Swiss Cheese Shortly Before Removing The Burgers From The Skillet; Serve On Hamburger Buns.