Separate beef into 8 equal portions. Use hands to lightly form into patties the size of your buns. Once you have formed the patties, take a thin slice of your cheddar cheese and place it in the center of one. Once you do that, grab another patty, and enclose the cheese. Season generously with a blend of salt and pepper on both sides. Repeat until you have 4 cheese-stuffed patties.
Take your oil and apply it to your skillet or flat top, sauté your onions until caramelized, and then remove.
Now that you have a hot cooking surface, add the patties and cook for 3 minutes until you get a good sear. Do not press the patties. After 3 minutes, gently flip the patties and then cover with more cheese, if desired. While you wait, lightly toast your buns.
To serve: Spread base of buns with sauce/condiments of choice. Top with lettuce and then hamburger patty. Pile over caramelized sautéed onions, sliced pickles, then more sauce/condiments. Top with a lid of bun. Serve immediately.