Preheat the oven to 350 F (176 C). Use butter to grease the bottom of a rimmed baking sheet.
Cut the buns in half horizontally. Place the bottom half of the buns on the baking sheet cut side up, and set it to the side.
To a small bowl, add the mayonnaise, ketchup, and mustard. Mix to combine, and set to the side.
Heat a large nonstick skillet over medium heat. Once hot, add the olive oil and swirl to coat the pan. Add the onion and saute for about 3 minutes (or until softened and translucent).
Add the ground beef and season with the salt, pepper, garlic powder, and onion powder. Cook for about 4 - 5 minutes (or until it is fully cooked and no pink remains), making sure to break the beef up into small crumbles as it cooks.
Once the beef is cooked, drain off the excess fat. Stir in the mayonnaise, ketchup, and mustard mixture.
Spread the ground beef mixture evenly across the bottom half of the slider rolls. Top with the cheddar cheese slices, and place the top half of the buns cut side down on top of the sliders. Press down slightly.
Brush the tops with melted butter, then sprinkle the sesame seeds over top.
Bake uncovered in the preheated oven for 12 - 15 minutes, or until the sliders are warmed through and the cheese is melted.
This recipe multiplies perfectly! Feel free to double, triple, or quadruple it (depending on how many people you’re serving).