Cook ground beef in a large skillet over medium-high heat with salt and pepper, breaking apart until browned and cooked through, about 10 minutes.
Preheat oven to 350°F and line a large baking sheet with parchment paper.
Slice slider rolls horizontally, keeping them connected. Place bottoms on the baking sheet and layer with American cheese slices followed by cooked beef.
Sprinkle diced onions evenly over the beef.
Place top buns back on, brush with melted butter, sprinkle sesame seeds on top, and bake for 12 minutes until golden and toasted.
Mix mayonnaise, mustard, vinegar, pickle relish, onion powder, garlic powder, and paprika in a small bowl until smooth to make Big Mac sauce.
After baking, carefully remove top buns. Layer shredded lettuce, drizzle Big Mac sauce, and add pickle slices on the bottom buns.
Replace the top buns, slice sliders, and serve immediately.