Preheat your oven to 350°F. Add 1 tablespoon of butter to a large pan over medium heat. Once melted, add the finely diced onion and cook until softened, about 3–4 minutes.
Add the ground beef to the pan and break it up finely as it cooks. Once the beef begins to brown, add in the salt, pepper, garlic powder, and onion powder. Stir to combine.
Continue cooking until the beef is fully browned. Drain excess grease, leaving just a small amount behind so the beef stays juicy (not dry)
Stir in the Worcestershire sauce and cook for another 2 minutes. (Optional: Once the beef has cooled slightly, stir in 1/4 cup of Mayonnaise to help the meat bind together. You can leave this out if you'd like, the meat will just be a little looser when packing into the bread for the sliders).
Prep the Hawaiian rolls. Keep them connected and slice the entire slab horizontally. Place the bottom half into a greased 9x13-inch baking dish
Add 4 slices of cheddar cheese over the bottom layer of rolls. You may have to slice pieces off and rearrange to make sure the cheese is in an even layer.
Spoon the beef mixture evenly over the cheese. Use a spoon or spatula to press it down firmly into an even layer so it stays together after baking. These make meaty sliders, but if you prefer a lighter version, you can leave a bit of the beef out and serve it on the side.
Add the remaining 4 slices of cheddar cheese on top of the beef, then place the top half of the rolls over everything
Melt the remaining 1 tablespoon of butter and brush it generously over the tops of the rolls. Sprinkle sesame seeds on top if desired
Bake for 12–15 minutes, or until the cheese is melted and the tops are golden. Let them rest for 5 minutes and then slice into individual sliders to serve.