Combine ingredients: In a large bowl, combine the ground chicken, chopped spinach, shredded white cheddar cheese, breadcrumbs, beaten egg, minced garlic, Worcestershire sauce, Italian herbs, salt, and pepper. Mix gently but thoroughly until everything is well combined.
Form patties: Divide the chicken mixture into 4 equal portions. Gently form each portion into a patty, about ¾ inch thick. Make a small indentation in the center of each patty to prevent them from bulging during cooking.
Cook burgers: Heat a large skillet over medium-high heat. You can add a little olive oil or cooking spray to the pan if desired. Add the chicken patties and cook for 5-7 minutes per side, or until cooked through and the internal temperature reaches 165°F (74°C).
Add cheese: During the last minute of cooking, top each burger with a slice of white cheddar cheese and let it melt.
Assemble burgers: Place the cooked chicken burgers on burger buns. Add your favorite toppings, such as lettuce, tomato, red onion, avocado, mayonnaise, and mustard.
Serve: Serve immediately.