Preheat oven to 350°F
Combine the beef and spices in a bowl.
2 pounds lean ground beef, 2 teaspoons garlic powder, 1 teaspoon kosher salt, 2 teaspoons ground black pepper
Press the beef into the bottom of a 9x13-inch baking dish into a flat and even layer.
Bake for 20 minutes. Drain the liquid and set aside.
In a large skillet set over medium-high heat add the olive oil. Add in the diced onion and stir to coat. Cook until onion is translucent and fragrant. Drain excess oil fully and set aside.
1 tablespoon olive oil, ½ white onion
Slice the rolls in half lengthwise. Place the bottom half in the same baking dish.
12 slider-sized Hawaiian rolls
Top the bottom half of the rolls with the cooked beef, then the onions, then slices of cheese in a single layer. Top with the top half of the rolls.
12 (¾-ounce) cheese snack bars
In a small bowl combine the melted butter and all other ingredients for the butter topping. (optional, see note)
¼ cup unsalted butter, ½ teaspoon kosher salt, 2 tablespoons brown sugar, 3 teaspoons Worcestershire sauce, 2 tablespoons Dijon mustard, ½ tablespoon sesame seeds
Brush the tops of the rolls liberally with melted butter (or pour it over) mixture and sprinkle the sesame seeds on top.
Bake for an additional 20 minutes, or until the bread is toasted and the cheese is melty.
Slice into individual sliders and serve hot. Enjoy!