01 - Preheat grill or large skillet to medium-high heat.
02 - Combine ground beef, kosher salt, black pepper, garlic powder, and onion powder in mixing bowl. Mix gently until just incorporated.
03 - Divide beef mixture into 12 equal portions and shape into small patties, making them slightly larger than buns to account for shrinkage during cooking.
04 - Grill or cook patties 2-3 minutes per side until browned and cooked to desired doneness.
05 - Place cheese slice on each patty during final minute of cooking. Cover to melt completely.
06 - Slice slider buns in half. Brush cut sides with melted butter and toast on grill or skillet until golden brown.
07 - Spread ketchup, mustard, and mayonnaise on bottom buns. Top with cheeseburger patties, pickles, and red onion slices. Add bun tops and sprinkle with sesame seeds if desired. Serve immediately.