Preheat the oven to 350°F. In a large pan on medium-heat, add the ground beef, half of the diced onion, salt, pepper, garlic powder, and onion powder. Cook until the beef is no longer pink and cooked through, about 5-7 minutes.
Carefully cut the rolls in half lengthwise with a serrated or sharp knife. Set aside.
In a small bowl, combine the mayo, relish, mustard, ketchup, onion powder and garlic powder and mix. Spread half of the sauce on the bottom layer of the rolls.
Top with the cooked beef, sliced cheese, lettuce, and pickles. Drizzle the remaining sauce on top and place the top half of bread rolls on the sliders.
Brush the melted butter on top of the sliders and then top with sesame seeds (optional).
Bake the sliders for 10-15 minutes or until the cheese has melted. Let sliders cool for a few minutes and then cut into 12 sliders.
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