Preheat oven to 350°F (175°C). Heat olive oil in a skillet over medium heat. Add the chopped onion and cook for 3–4 minutes until soft and slightly golden. Add the ground beef, breaking it up with a spatula. Cook until no pink remains, then stir in garlic powder, paprika, salt, and pepper. Drain excess grease if needed.

Cut the slab of slider buns in half horizontally (keeping them connected). Place the bottom halves in your baking dish. Spread the cooked beef mixture evenly over the buns, then layer cheese slices on top. Add the top halves of the buns.

Mix melted butter and Worcestershire sauce in a small bowl. Brush this generously over the tops of the buns, letting some drip down the sides. Sprinkle with sesame seeds if using. Cover the dish with foil and bake for 15 minutes.

Remove the foil and bake another 5–7 minutes until the tops are golden. Let cool slightly before slicing into individual sliders.