In a small bowl, combine the salt and pepper. Set aside.

Divide the beef into 4 equal portions and halve each portion for a total of 8 equal portions.

Gently form each portion into a 4-inch wide x ¼-inch deep disc and season both sides of each patty with the salt and pepper mixture.

Place 1 slice of cheese in the middle of 4 patties. Fold the cheese corners to the middle of each cheese slice so there is no overhang.

Use your fingers or a spatula to lift a patty (without cheese) and place it on top of one of the patties with cheese. Pinch the edges together to ensure the cheese stays inside the patty when cooked/melted. Repeat this process until all 4 cheese-filled patties are formed.

Heat the oil in a large cast-iron skillet over medium heat for 2 minutes. Add the burgers and cook for 3-4 minutes until a good sear is formed and the edges begin to brown. Gently flip the burgers over and sear the second side, about 3-4 more minutes.

While the burgers cook, toast the buns, if desired.

Transfer the burgers to a paper towel-lined plate.

Assemble the burgers and add your favorite burger toppings. (Be careful when taking the first bite - the hot cheese can squirt out.) Serve and enjoy!