Add ground beef to a bowl and divide into eight equal pieces and form into balls.
Cut the buns in half. Melt butter in a pan large enough to hold each half of the four burger buns. Toast lightly. Set aside.
Heat pan over medium-high heat. Once hot, add four. of the burger balls. Using the flat side of a spatula, smash each burger patty. Season with salt and pepper. Sear for two minutes. Flip and top each with a slice of cheddar cheese. Sear two more minutes.
On the bottom buns, add a generous spoonful of the sauce and top each with the first patties.
Add the remaining four burger balls to the pan. Using the flat side of the spatula smash the burger patties. Season with salt and pepper. Sear for two minutes. Flip and top each with a slice of American cheese. Sear for two more minutes.
Add the second patties on top of each of the first patties. Top the second patties with another generous dollop of sauce, and the top buns.