01 - Preheat a grill or skillet over medium-high heat.
02 - In a bowl, gently mix the ground beef with salt, pepper, garlic powder, and onion powder. Do not overmix.
03 - Divide the beef into 8 equal portions and shape into small patties, slightly larger than the buns (they will shrink as they cook).
04 - Grill or pan-fry the patties for 2-3 minutes per side, until cooked to your desired doneness.
05 - Place a slice of cheese on each patty during the last 30 seconds of cooking to melt.
06 - Meanwhile, brush the cut sides of the slider buns with melted butter and toast them on the grill or in a pan until golden brown.
07 - Assemble the sliders: Place a patty on each bun bottom, top with pickle slices, onion (if using), and a dab of mustard (if desired). Cover with the bun tops.
08 - Serve immediately while hot.