**Prepare the Beef**
In a mixing bowl, combine ground beef and onion soup mix. Cook the beef in a large skillet over medium heat, breaking it into crumbles until fully browned. Drain any excess grease.
**Make the Special Sauce**
In a small bowl, whisk together mayonnaise, ketchup, mustard, sweet pickle relish, garlic powder, onion powder, and paprika until smooth. Set aside.
**Assemble the Sliders**
- Preheat the oven to 350°F (175°C).
- Slice the slider buns in half horizontally, keeping the top buns attached. Place the bottom buns in a baking dish.
- Spread a layer of special sauce on the bottom buns.
- Evenly distribute the cooked beef over the sauce.
- Layer cheese slices over the beef.
- Add shredded lettuce and pickle slices.
- Top with the upper buns.
**Bake the Sliders**
Brush the tops of the buns with melted butter and sprinkle with sesame seeds. Cover the dish with foil and bake for 10 minutes. Remove the foil and bake for another 5 minutes, or until the cheese is melted and the tops are golden.
**Serve**
Slice into individual sliders and serve warm with extra special sauce on the side.