1lb Ground Beef
4 Hamburger Buns
2 tablespoons Unsalted Butter, melted
Salt and Pepper
Sliced Cheddar or American Cheese
Onion
Lettuce
Tomatoes
Sautéed Mushrooms
Divide the meat into 4 even portions and form into pucks about 2 inches high and 2.5 inches wide. Refrigerate until ready to use.
Open the buns, but do not split the hinges. Brush lightly with the butter, then toast under a hot broiler or in a toaster oven until golden brown, about 1 minute. Set aside.
Using a wadded-up paper towel, rub the inside of a 12-inch cast-iron skillet with vegetable oil, then heat over medium-high heat until just beginning to smoke. Season the beef pucks on the top with salt and pepper, then place seasoned side down into the skillet.
Using a wide heavy spatula, press down onto each one until it is roughly 4 to 4.5 inches in diameter, and a 1/2 thick. Season the tops with salt and pepper. Cook without moving the burgers, until a golden brown crust develops at the bottom, about 1 1/2 minutes. Use the edge of the spatula to carefully scrape up the and flip the patties one at a time, making sure to get all the browned bits.
If using onions, add to the tops of the burgers, then cover each with a cheese slice.
Continue to cook until the patties are the desired doneness — about 30 seconds longer for medium-rare.
Top the patties as desired, transfer to buns and serve.