►Cut each slice of cheese in half, then in half again to form 4 squares. Stack squares on top of each other to form 4 stacks. Set aside.
►Combine ground chuck, Worcestershire, salt, garlic powder, and pepper in a large bowl. Mix with your hands until evenly combined. Divide meat into 8 equal portions.
►Lay out a piece of plastic wrap and place a beef portion on it. Top with another piece of plastic wrap and flatten beef into a ¼-inch-thick patty. Repeat with remaining beef portions.
►Place 1 stack of cheese in center of 4 patties. Top each with a second patty and pinch edges to form a tight seal. Cup each patty in your hands to round out edges, then press to flatten slightly into a single, thick patty. Transfer the 4 cheese-stuffed patties to a plate. Season generously with additional salt and pepper.
►Warm a large cast-iron skillet or griddle over medium-high heat. Add just enough vegetable oil to coat bottom of skillet. Place patties in heated skillet and cook undisturbed (do not press down on patties) for 3 to 4 minutes. Flip patties and cook on second side for an additional 3 to 4 minutes, until cooked through.
►Transfer cooked patties to a plate, tent loosely with foil, and rest for 5 minutes. Serve on toasted buns with pickles, onions, and plenty of napkins