Preheat oven to 400 degrees.
Salt and pepper the bottom of ground beef and place on large rimmed baking sheet (I use a 10 ½" x 15 ½" baking sheet), and flatten into an even layer ~½" thick.*
Sprinkle salt and pepper on the top of the beef and place it in the oven for 20 minutes, or until the interior reaches 160 degrees.
While beef is baking cut the dinner rolls in half to separate the top from the bottoms.
When beef patty is finished baking, remove it from the oven, discard the grease, and place the patty on the bottom half of the buns. Top the patty with enough cheese to cover and place the baking sheet back in the oven for 2 minutes, or until the cheese is melted.
Once the cheese has melted, remove from the oven and sprinkle generously with diced onion, top with pickles, ketchup, mustard, and cover with the top half of the buns. Place back in the oven for another 1-2 minutes, to allow top buns to warm.
Remove from the oven, cut into individual sliders, and serve.