Heat a skillet over medium heat and add the vegetable oil. Once heated, add the ground beef and chopped onion.
Break apart the beef with a wooden or silicone spatula. Season with salt, pepper, and garlic powder. Mix everything together in the pan, and cook until the beef is browned. Drain the grease from the beef and set it aside.
Preheat the oven to 350°F. Butter the bottom of a baking sheet.
Without separating the individual buns/rolls, cut the buns in half horizontally to create two sheets: top buns and bottom buns.
Spoon the ground beef onto the bottom buns and spread it in an even layer. Add a slice of cheese to each roll, overlapping the slices for extra cheesiness.
Place the top buns over the cheese. Melt the butter in a small saucepan or a microwave-safe bowl and spread it over the tops of the buns. Sprinkle with sesame seeds.
Bake for 10 to 12 minutes or until the buns are golden and cheese is melted. Enjoy!
Notes
This recipe makes 6 servings, if you consider 2 sliders per serving. This recipe is easy to double if you want to make a bigger batch to serve a crowd!