Make the spread by combing all of the ingredients in a small bowl. Set this aside until needed.
Make eight patties by rolling 2-ounce portions of beef into balls and forming them into 4-inch circles on wax paper.
Preheat two large sauté pans over medium/low to medium heat. Start at medium/low and then turn up the heat if needed after 5 minutes of pre-heating.
To prepare each burger, separate a hamburger bun and place the face of the top and bottom bun on one of the hot pans to toast. The buns are done when the faces are significantly darkened and crispy.
Cook the beef by placing two patties in the other hot pan. Add a generous sprinkling of salt and a pinch of coarse ground pepper. Cook for 2 minutes, then flip each patty over and salt and pepper each one again. The beef should be nicely seared.
Immediately after flipping the beef add a slice of American cheese on top of each patty. Before adding the cheese, fold about one-quarter of it over and place it onto a patty with the folded side underneath, but offset so that about 1/2-inch of the beef patty is showing where the cheese is folded. This gives you the "smile." Place the toasted top bun on top of one of the burgers and the sliced onion on the other. Cook the patties for another 2 minutes.
While the patties cook, prepare the bottom of the hamburger by adding about 1 1/2 tablespoons of spread onto the face of the toasted bottom bun. Stack the tomato slice on next. Pick up a small handful of lettuce and press it into the palm of your hand to compact it so that the hamburger isn't too tall, then add it on top of the tomato.
When the patties are done, use a spatula to stack the top patty (with the bun) onto the onion on the second patty. Use your spatula to move this whole stack off the pan and onto the bottom of the sandwich. Wrap the burger with wax paper or sandwich paper, if you like, and serve.