Arrange a rack in the middle of the oven and heat the oven to 400ºF. Stack 4 slices American cheese. Cut in half, then cut each piece in half again to form 4 stacks of squares.

Place 1 ½ pounds ground beef, 1 ¼ teaspoons kosher salt, ½ teaspoon garlic powder, ½ teaspoon Worcestershire sauce, and ¼ teaspoon black pepper in a large bowl. Gently mix with your hands until just evenly combined.

Divide the beef into 8 portions (3 ounces each) and form each into a ball.

Form 1 juicy lucy at a time: Using your fingertips, press 2 portions into ¼-inch-thick patties that are about 1 inch wider in diameter than the hamburger buns. Top 1 patty with 4 pieces of cheese, overlapping the slices to cover the patty but leaving a ½-inch border. Place the second patty over the cheese-topped patty. Pick up the Juicy Lucy and pinch the edges to form a tight seal. Cup the stuffed patty with your hands to round out the edges, and press on the top to flatten slightly into a single thick patty. Transfer to a plate. Repeat with the remaining patties and cheese to form 4 stuffed patties in total.

Heat 1 tablespoon vegetable oil in a large cast iron skillet or frying pan over medium heat until shimmering, 3 to 4 minutes. If using a 10-inch pan, place 2 patties in the pan; if using a 12-inch or larger, add all 4 patties. Cook undisturbed (do not press down on the patties) until dark golden-brown on the bottom, about 4 minutes. Using a spatula, flip the patties and cook until the second side is dark golden-brown and the patties are cooked through, about 4 minutes.

Transfer to a clean plate. Let rest in a warm place or tent loosely with aluminum foil while you toast the buns. Split 4 hamburger buns, place cut-side up on a baking sheet, and toast until starting to brown around the edges, 4 to 5 minutes.

Place a patty on each bun bottom, top with a few pickle slices, and close with the bun top.