01 - Combine shredded cheddar cheese, softened cream cheese, mayonnaise, diced pimentos, garlic powder, smoked paprika, cayenne pepper if using, and a pinch of salt and black pepper in a medium bowl. Mix thoroughly until smooth and homogeneous.
02 - In a large bowl, gently combine ground beef with Worcestershire sauce, salt, and black pepper. Divide the mixture into 8 equal portions and flatten each to a 4-inch diameter patty.
03 - Place a heaping tablespoon of the pimento cheese mixture in the center of 4 patties. Top with the remaining patties and seal the edges tightly to fully enclose the filling. Reshape gently into thick, uniform burgers.
04 - Preheat a grill or grill pan to medium-high heat. Lightly oil the cooking grates to prevent sticking.
05 - Place the stuffed burgers on the preheated grill. Cook for 6 to 7 minutes per side or until the beef is fully cooked and the filling is melted inside.
06 - Toast burger buns, cut sides down, on the grill for 1 minute or until golden if desired.
07 - Assemble each burger with lettuce leaves, tomato slices, red onion, and pickles as preferred. Serve hot immediately.