Divide the ground beef into 4 equal portions, gently shape into patties without overworking, and press a shallow indent in the center of each patty with your thumb.
Season both sides of each patty with garlic powder and smoked paprika.
Grill the patties over medium-high heat for 4 to 5 minutes per side, flipping once, until they reach 160°F / 71°C internal temperature.
Place one cheese slice on each patty during the last 60 seconds of cooking and cover the grill to melt.
Toast the buns cut-side down on the grill for 1 to 2 minutes until golden.
Mix the barbecue sauce and mayonnaise together to make the BBQ sauce.
Assemble each burger with bottom bun, BBQ sauce, lettuce, patty with cheese, red onion, and top bun.