Preheat oven to 400°F and line a baking sheet with parchment paper.
In a large bowl, combine the lean ground turkey, egg, panko breadcrumbs, Italian herbs, salt, and pepper. Mix thoroughly until well incorporated.
Divide the turkey mixture into two equal portions. Flatten each portion into a patty about half an inch thick.
Place a piece of mozzarella cheese in the center of each patty and gently fold the mixture around the cheese, sealing it completely to enclose the mozzarella.
Lightly shape the patties into burgers, ensuring an even distribution of the mixture for uniform baking.
Place the stuffed turkey burgers on the prepared baking sheet and bake for 18-22 minutes, or until the internal temperature reaches 165°F and the outside is nicely browned.
While the burgers bake, prepare the toppings by washing and slicing the lettuce, tomato, and red onion.
Toast the whole wheat bun if desired.
Assemble the burger by placing the baked turkey patty on the bun and topping with fresh lettuce, tomato, and red onion slices.
Serve immediately and enjoy your crispy baked mozzarella-stuffed turkey burger.