Combine 1 tablespoon Worcestershire sauce, 3 teaspoons of mustard, and half of the onions in a large bowl. Mix in the ground beef, and mold into patties (about 4, depending upon how big you make the patties).

Grill, covered, over medium heat, for 6 to 9 minutes on each side or you can pan fry them to desired doneness (don’t turn them too often—about 4 minutes on each side should give you a medium burger).

Cook mushrooms while burgers are cooking. In a small skillet, over medium heat, melt butter and add sliced mushrooms, cook until done.

Mix the remaining 1 tablespoon Worcestershire sauce, cream cheese, the remaining 1 teaspoon mustard, and the parsley. Spread over the cooked burgers. Top with sauteed mushrooms, Swiss cheese slices, sliced avocado and (if desired) top with the remaining onions.

Serve with mayo, lettuce and tomatoes on hamburger buns if desired.

Yummy!

Happy cooking!