01 - In a large mixing bowl, combine the ground beef, basil pesto, minced garlic, kosher salt, and black pepper. Gently fold the mixture until evenly incorporated, being careful not to overwork the meat. Divide into 4 equal portions and shape into uniform patties, pressing a slight indent in the center to prevent puffing during cooking.
02 - In a small bowl, whisk together the mayonnaise, finely minced garlic, fresh lemon juice, and chopped parsley. Season with salt and pepper to taste. Cover and refrigerate to allow the flavors to meld while you cook the burgers.
03 - Preheat a grill or cast-iron skillet over medium-high heat. Place the burger buns cut-side down and toast for 1 to 2 minutes until golden brown and lightly crisp. Remove and set aside.
04 - Place the formed patties on the hot grill or skillet. Cook for 4 to 5 minutes per side, or until the internal temperature reaches your preferred doneness. During the final minute of cooking, lay a slice of provolone or mozzarella cheese atop each patty and cover with a lid or foil to allow the cheese to melt evenly.
05 - Spread a generous layer of the creamy garlic mayo on the bottom half of each toasted bun. Layer on a lettuce leaf, followed by the cheesy pesto patty, a slice of tomato, and a few rings of red onion. Add an extra spread of mayo on the top bun if desired, then close the burger.
06 - Serve the burgers immediately while hot, accompanied by your favorite side dishes such as crispy fries, a fresh salad, or coleslaw.