01 - Preheat oven to 350°F.
02 - In a medium bowl, gently combine ground beef, garlic powder, onion powder, salt, and black pepper. Mix lightly to avoid overworking the meat.
03 - Press seasoned beef mixture evenly into a 9x13-inch baking dish, creating a uniform layer approximately 1/2 inch thick.
04 - Bake for 10 to 12 minutes until cooked through. Drain excess fat and set aside.
05 - Slice slider buns horizontally. Arrange bottom halves on a parchment-lined baking sheet.
06 - Place cooked beef slab over bun bottoms. Top with American cheese halves, pickle slices, and diced onion if desired.
07 - Drizzle ketchup and mustard evenly across the layered toppings.
08 - Cover with bun tops. Brush tops with melted butter and sprinkle sesame seeds if using.
09 - Return to oven for 5 minutes until cheese melts and buns are lightly toasted.
10 - Remove from oven, cut into individual sliders, and serve immediately while warm.