Divide ground beef into 4 equal portions and shape into patties about ¾ inch thick. Season with salt and pepper.
Heat a grill or skillet over medium-high heat. Cook patties for 3–4 minutes per side, until desired doneness.
Add a slice of cheese on each patty during the last minute of cooking, cover, and let it melt.
Toast burger buns lightly on the grill or in a skillet.
Spread mayonnaise, ketchup, and mustard on the buns. Layer with lettuce, tomato, onion, and the cheesy beef patty.
Top with pickles or bacon if desired. Close the bun and serve immediately.