Preheat and Prep: First, preheat your oven to 350°F (175°C). Then, lightly grease a 9x13 inch baking dish.

Cook the Beef: In a large skillet over medium-high heat, brown the ground beef and chopped onion. Break up the beef with a spoon or spatula as it cooks.

Drain and Season: Once the beef is fully cooked and no longer pink, drain off any excess grease. Stir in the Worcestershire sauce, ketchup, mustard, garlic powder, salt, and pepper.

Simmer: Reduce the heat to low and let the mixture simmer for about 5 minutes, stirring occasionally. This allows the flavors to meld together.

Prepare the Rolls: While the beef is simmering, slice the Hawaiian rolls in half horizontally, keeping the top and bottom halves connected as one large piece. It's like you're making a giant sandwich.

Assemble the Sliders: Place the bottom half of the rolls in the prepared baking dish.

Add the Beef: Evenly spread the cooked beef mixture over the bottom layer of rolls.

Add Cheese: Top the beef with the cheese slices.

Cover with Rolls: Place the top half of the rolls on top of the cheese.

Brush and Sprinkle: Brush the melted butter evenly over the top of the rolls. If you're using them, sprinkle sesame seeds on top.

Bake: Cover the baking dish with aluminum foil and bake for 15 minutes.

Uncover and Bake: Remove the foil and bake for another 5-10 minutes, or until the cheese is melted, bubbly, and the tops of the rolls are golden brown. Keep a close eye on them to prevent burning.

Cool and Serve: Let the sliders cool slightly before slicing and serving. This will help them hold their shape better.