01 - In a mixing bowl, combine ground beef, basil pesto, minced garlic, salt, and pepper. Gently fold until just incorporated—avoid overmixing to keep the texture tender. Divide the mixture into 4 equal portions and shape into uniform patties, pressing a slight indentation in the center to prevent puffing during cooking.
02 - Whisk together mayonnaise, finely minced garlic, lemon juice, and chopped parsley in a small bowl. 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 patties on the grill or skillet and cook for 4 to 5 minutes per side, adjusting time based on your preferred doneness. During the final minute of cooking, lay a slice of provolone or mozzarella cheese on each patty and cover with a lid or foil to allow the cheese to melt evenly.
05 - Spread a generous layer of creamy garlic mayo on the bottom half of each toasted bun. Layer a lettuce leaf, followed by the cheesy patty, a slice of tomato, and a few rings of red onion. Add additional mayo to the top bun if desired, then close the burger.
06 - Serve the burgers immediately while hot, paired with your choice of side dishes such as fries, a mixed green salad, or roasted vegetables.