In a mixing bowl, combine turkey, onion powder, garlic powder, worcestershire and salt and pepper. Form into 4 4-inch patties.
Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add patties; cook 4 minutes on each side or until done.
Heat oil in a medium skillet over medium-high heat. Add onion, salt, pepper, and mushrooms; sauté 3 minutes. Sprinkle flour over mushroom mixture; cook 1 minute, stirring constantly. Stir in beer; cook 30 seconds or until thick. Remove from heat; keep warm.
When patties are done, remove from large skillet. Wipe pan clean; heat over medium-high heat.
Coat 1 side of each bread slice with cooking spray. Place 4 bread slices, coated sides down, in pan. Top each with 1 patty, 1 cheese slice, and one-fourth of mushroom mixture. Top with remaining bread slices; coat with cooking spray. Cook 2 minutes on each side or until browned.