Divide the ground beef into four equal portions and gently form each one into a ball. Avoid overworking the meat to keep it tender.
Preheat your griddle or cast-iron skillet over medium-high heat until very hot. Spread butter onto the buns and lightly toast them, then set them aside.
Place each meatball on the griddle. Flatten sharply into a patty using a strong spatula. Season with salt and pepper.
Cook for 2-4 minutes until the edges are brown and crispy. Flip the burgers, add a slice of cheese to each, and cook for another 1-2 minutes.
Set the cheese-topped patties on the bottom buns. Add toppings if desired. Cover each with the top buns and serve immediately.