Line a baking sheet with parchment paper and set it aside.
Mix the burgers. In a large bowl, combine the ground chicken, grated onion, salt, black pepper, breadcrumbs, egg yolk, Worcestershire sauce, garlic powder, and Italian seasoning. Mix together until everything is well combined.
2 lb ground chicken (93% lean), ½ medium onion, 2 tsp kosher salt, 1 tsp freshly ground black pepper, ¾ cup panko breadcrumbs, 1 large egg yolk, 1 tbsp Worcestershire sauce, 1 ½ tsp garlic powder, 1 tsp dried Italian seasoning
Form the mixture into 8 even balls, placing each one on the prepared parchment paper. Press the balls into a patty about ½-inch thick. Set in the refrigerator to chill for 30 minutes.
Cook the burgers. Preheat the grill on medium-high for 15 minutes. Alternatively, preheat a grill pan over medium heat for 5-7 minutes. Brush with neutral oil. Grill the patties until browned with the internal temperature reaching 165°F, 4-5 minutes per side. If melted cheese is desired, place a slice of cheese on each patty during the last 1-2 minutes of cooking.
Assemble. Place a burger on each bun and top with desired toppings: cheese, lettuce, tomato, and burger sauce.
Watch the moisture – When you grate the onion, try not to add all the excess liquid from it. Too much moisture can make the patties soggy and hard to grill.Make a divot – Use your thumb to gently press a small indent in the center of each patty. This helps prevent them from puffing up or shrinking too much on the grill.Chill the patties before grilling them – Let the patties rest in the fridge for at least 30 minutes. This helps them firm up and hold their shape on the grill.Shape the patties with a biscuit cutter – Use a round cutter to get evenly sized patties. Press the mixture into the cutter with wet fingers. Dipping them in water keeps the meat from sticking and makes shaping way easier.