01 - Preheat oven to 350°F.
02 - In a medium bowl, gently mix ground beef, garlic powder, onion powder, salt, and pepper. Do not overwork the meat.
03 - Press beef mixture evenly into a 9x13-inch baking dish to form a single slab about 1/2 inch thick.
04 - Bake for 10–12 minutes, until just cooked through. Drain excess fat and set aside.
05 - Slice slider buns in half horizontally. Place bottom halves on a parchment-lined baking sheet.
06 - Place cooked beef slab on top of the buns. Layer with cheese slices, pickle slices, and diced onion (if using).
07 - Drizzle ketchup and mustard evenly over the toppings.
08 - Cover with top halves of the buns. Brush tops with melted butter and sprinkle with sesame seeds if desired.
09 - Return to oven for 5 minutes, until cheese melts and buns are slightly toasted.
10 - Remove from oven and cut into individual sliders. Serve warm.