Preheat your oven to 400°F and line a baking sheet with parchment paper for easy cleanup.
Slice the zucchini into rounds and set aside for steaming later.
In a shallow bowl, whisk the egg until smooth. In a second bowl, combine the panko breadcrumbs, garlic powder, dried oregano, sea salt, and black pepper.
Dip the chicken breast into the egg wash, then press it firmly into the panko mixture until it is evenly and thoroughly coated.
Place the chicken on the prepared baking sheet, drizzle with olive oil, and bake for 15 minutes.
Remove the chicken from the oven, spoon the marinara sauce over the top, and sprinkle with the mozzarella cheese.
Return the chicken to the oven and bake for an additional 5-7 minutes until the cheese is melted and bubbly.
While the chicken finishes, steam the zucchini rounds in a steamer basket for 4-5 minutes until tender-crisp.
Serve the crispy chicken garnished with parmesan cheese alongside the steamed zucchini.