Preheat your oven to 400°F (200°C). This ensures your chicken cooks evenly and gets that beautiful golden color.
Place the chicken breasts between two pieces of plastic wrap on your cutting board. Gently pound them to an even thickness using a meat mallet or rolling pin.
In one bowl, beat the egg. In another bowl, combine the panko breadcrumbs, grated Parmesan cheese, dried oregano, garlic powder, kosher salt, and black pepper. Mix well.
Dip each chicken breast into the egg, allowing any excess to drip off. Then, coat it thoroughly in the breadcrumb mixture.
Place the coated chicken breasts on a baking sheet lined with parchment paper. Drizzle the olive oil over the top.
Bake the chicken in the preheated oven for about 20 minutes or until cooked through and the coating is golden brown.
Remove the chicken from the oven and spoon the marinara sauce evenly over each breast. Sprinkle the shredded mozzarella cheese on top.
Return the chicken to the oven and bake for an additional 5-7 minutes, or until the cheese is melted and bubbly.
Once baked, remove from the oven and let it rest for a few minutes. Garnish with minced parsley if desired.