Turn the oven broiler on to high. Line one half sheet pan with parchment paper, a quarter sheet pan with non-stick aluminum foil, a quarter sheet pan with paper towels, and a quarter sheet pan with parchment paper.
Cut the slider buns in half horizontally, making sure to keep the slabs intact, and place each half on the prepared half sheet pan with parchment paper, cut side up. Melt two tablespoons of butter in the microwave, then brush the melted butter over the tops of each slab. Broil in the oven for 30-90 seconds until lightly toasted. Keep an eye on them, they can burn quickly. Set aside until ready to build the sliders.
Preheat the oven to 350°F. Transfer the ground beef to a large bowl. Add garlic powder, onion powder, black pepper, and Kosher salt. Put on a pair of vinyl gloves and use your hands to mix the spices into the meat. Transfer the meat mixture to the white tray that the slider buns came in and press it into an even layer. Then, lower the sides of the tray and press the meat out so it goes about half an inch past each side.2 Flip the shaped meat onto the foil-lined half sheet pan and peel the slider tray away from the meat. Bake for 15-20 minutes in a 350°F oven.
After the meat has baked, use two large spatulas to transfer the meat to the paper towel-lined sheet pan. Cover the meat with more paper towels to soak up the grease.
Spoon a few tablespoons of burger sauce over both toasted halves of slider buns. Transfer the bottom buns to the parchment-lined quarter sheet pan. Top with five slices of American cheese, breaking one of the slices in half, to cover the entire surface. Then top the cheese with seven slices of cooked bacon.
Then, carefully transfer the cooked meat slab to on top of the bacon. Top with five more slices of cheese, breaking one of them in half, to cover the entire surface of the meat with an even layer. Top the cheese with seven more slices of bacon. Place the sauced slider bun tops on the bacon.
Cover the sliders loosely with a piece of non-stick aluminum foil. Bake in a 350°F oven for 15-20 minutes, or until cheese is melted.
Remove from the oven and allow to cool for 5-7 minutes before cutting into individual sliders.3