Heat a skillet over medium heat and add the vegetable oil. Once the oil is warm, toss in your ground beef and chopped onions. Use a wooden or silicone spatula to break apart the beef into smaller pieces. Season it all with salt, pepper, and garlic powder for some extra flavor. Stir occasionally, and cook until the beef is browned and the onions are soft.
Once the beef is cooked, drain any excess grease from the pan, and set the beef mixture aside for a moment.
Preheat your oven to 350°F. Grab a baking sheet and butter the bottom to prevent sticking. Without pulling apart the individual rolls, carefully slice your Hawaiian rolls horizontally. This will give you two large sheets: one for the tops and one for the bottoms.
Place the bottom sheet of buns on the prepared baking sheet. Spoon the cooked beef mixture over the bottom buns, spreading it evenly. Then, lay your slices of mild cheddar cheese on top. Feel free to overlap the slices a bit for extra cheesiness! Once the cheese is in place, put the top buns back on.
Melt the butter in a microwave-safe bowl, then generously brush it over the tops of the buns. Sprinkle with sesame seeds for that perfect classic burger touch.
Pop the sliders in the oven and bake for 10-12 minutes, or until the tops of the buns are golden brown and the cheese is gooey and melted. Once baked, they’re ready to be devoured!