Preheat your oven to 400°F and lightly grease a baking sheet with olive oil.
Slice the chicken breast horizontally to form an even, thinner cut for quicker cooking. Season both sides with salt, pepper, and garlic powder.
In a shallow bowl, beat the egg. In another plate, spread out the whole wheat breadcrumbs.
Dip the chicken first into the egg, then coat it evenly with the breadcrumbs.
Place the breaded chicken on the baking sheet, drizzle a little extra olive oil over the top, and bake for 20-25 minutes or until the chicken reaches an internal temperature of 165°F.
A few minutes before the chicken finishes, place a slice of fresh mozzarella on top of the chicken to allow it to melt slightly.
Toast the whole wheat bun lightly in the oven or on a skillet.
Assemble the burger by placing the crispy, cheesy chicken on the bottom bun, add any additional toppings if desired, then cap with the top bun.
Serve immediately and enjoy your crispy mozzarella chicken burger.