Cut each cheese slice evenly into 4 squares; arrange in 4 stacks with 6 slices each.
In a large mixing bowl combine ground beef, garlic, Worcestershire, salt and pepper; mix by hand.
Form beef mixture into 8 thin patties on a large sheet pan. With your thumb, press an indented well in the center of 4 patties and put the portioned cheese in the wells. Encase the cheese with the remaining 4 patties, hand forming your burger to a uniform shape with sealed edges. Refrigerate at least 30 minutes before grilling.
Spray burgers with a light coat of cooking spray. Grill or pan sear over high heat 3 minutes per side. Transfer to cool side of grill or 375°F oven to finish cooking to an internal doneness of 160°F (5 to 8 minutes). Remove from grill and rest at least 3 minutes for cheese to set.