01 - In a large bowl, mix ground turkey, onion, garlic, Dijon mustard, Worcestershire sauce, salt, pepper, and parsley until just combined, avoiding overmixing.
02 - Shape the mixture into 4 equal patties, slightly larger than the buns.
03 - Heat olive oil in a skillet or grill pan over medium heat.
04 - Cook patties for 5 to 6 minutes per side until golden brown and internal temperature reaches 165°F.
05 - Place a slice of cheddar on each patty during the last minute of cooking and cover to melt.
06 - Toast the burger buns until golden brown.
07 - Spread mayonnaise and ketchup on buns if desired, then layer lettuce, tomato, turkey patty with melted cheese, and pickle slices. Top with bun.
08 - Serve immediately while warm.