Preheat oven to 375 degrees F. In a medium mixing bowl, combine ground beef, worcestershire sauce, salt, pepper, and garlic powder. Mix by hand until fully combined.

Press into the bottom of a 10 x 6 baking pan. Cook for 20 minutes. Drain excess liquid and allow the patty to drain on a bed of paper towels.

While the meat cooks, saute the mushrooms. Add mushrooms, onions, and 2 tablespoons of butter to a medium sized skillet over medium heat. Cook for 6-8 minutes, stirring frequently, until onions are translucent and the mushrooms are tender. When done, remove from heat and set aside.

Using a bread knife, carefully cut the hawaiian rolls into two equal portions, a top and a bottom, by cutting through the center, all the way around. You do not need to break apart the individual rolls.

Add the patty to the bottom roll. Top with mushrooms and onions. Add cheese slices before topping with the top half of the rolls.

In a small mixing bowl, melt the remaining butter. Use a silicone brush to coat butter on the tops of the buns. Top with sesame seeds.

Bake for 12-15 minutes or until the cheese has fully melted and the buns are toasted golden brown. When done, serve immediately.