In a bowl, gently mix ground beef, blue cheese crumbles, salt, garlic powder, and pepper. Avoid over-mixing to keep the patties tender.
Divide the mixture into 4 equal parts and form into patties. Make a small indentation in the center of each patty to ensure even cooking.
Preheat the grill to medium-high heat. Grill the patties for about 4-6 minutes on each side or until they reach an internal temperature of 160°F.
Toast the hamburger buns lightly. Spread mayonnaise on the buns (if using), then add lettuce, a slice of tomato, and the grilled patty. Serve immediately.