Preheat your oven to 350°F (175°C). While it's heating up, grab a 9x13 baking dish and give it a quick spray with cooking spray. Nothing ruins sliders like having them stick to the pan!
Without separating the rolls, slice the entire package in half horizontally with a serrated knife. Think of it as creating one giant top bun and one giant bottom bun. Place the bottom half in your baking dish.
In a large bowl, combine the ground beef with Worcestershire sauce, ketchup, garlic powder, onion powder, salt, and pepper. Mix with your hands until just combined. Don't overwork it – that's how you get tough burgers!
Heat a large skillet over medium-high heat. When hot, add the beef mixture and cook for about 5-7 minutes, breaking it up with a wooden spoon as it cooks. You want it to look like taco meat when you're done – small, even crumbles that are no longer pink.
Drain off excess fat if necessary. Nobody wants soggy slider buns!
Evenly spread the cooked beef over the bottom half of the rolls in the baking dish. Is your mouth watering yet? Because mine is.
Layer the cheese slices to completely cover the beef. Feel free to overlap them – there's no such thing as too much cheese here.
Sprinkle diced onions (if using) and arrange pickle chips over the cheese layer.
Place the top half of the rolls over everything to complete your sliders.
In a small bowl, mix the melted butter with garlic salt and brush it all over the tops of the rolls. Sprinkle with sesame seeds.
Cover with foil and bake for 10 minutes, then remove the foil and bake for another 5 minutes until the tops are golden brown and the cheese is completely melted.
Let cool for 2-3 minutes, then use a sharp knife to cut along the lines of the rolls to separate into individual sliders. Serve immediately and prepare for the compliments!