Preheat the oven to 350°F (175°C) and lightly grease a baking dish or sheet pan.

In a bowl, mix the ground beef with salt, black pepper, garlic powder, onion powder, and Worcestershire sauce until just combined.

Cook the beef in a skillet over medium heat, breaking it up with a spoon, until browned and cooked through. Drain excess grease if needed.

Slice the slider buns in half horizontally and place the bottom halves in the prepared baking dish.

Spread the cooked beef evenly over the bottom buns, then top with cheddar cheese slices. Add diced onion if using.

Place the top halves of the buns over the cheese. Brush the tops with melted butter and sprinkle with sesame seeds.

Cover loosely with foil and bake for 10 minutes. Remove the foil and bake for 3 to 5 more minutes, until the tops are golden and the cheese is melted.

Remove from the oven, separate into sliders, and serve warm with pickles, ketchup, and mustard.