01 - Heat grill, grill pan, or skillet to medium-high temperature.
02 - Combine ground beef, salt, pepper, and garlic powder in mixing bowl. Divide into 8 equal portions and shape into patties approximately 2.5 inches in diameter.
03 - Brush cut sides of buns with melted butter. Place cut side down on grill or skillet and toast until golden brown, 1-2 minutes. Set aside.
04 - Cook beef patties 2-3 minutes on first side. Flip, top each with cheese slice, and cook 2 additional minutes until cheese melts and patties reach desired doneness.
05 - Spread mayonnaise and/or ketchup on bottom buns. Place cheesy patties on buns, top with pickle slices and onion if desired, then cover with top buns.
06 - Serve immediately while warm.