Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it with cooking spray.
In a shallow bowl, combine the whole wheat breadcrumbs, grated Parmesan cheese, dried Italian seasoning, garlic powder, salt, and black pepper.
In another shallow bowl, beat the large egg.
Dip each chicken breast into the beaten egg, allowing excess to drip off, then dredge in the breadcrumb mixture, pressing gently to adhere the coating evenly.
Place the coated chicken breasts on the prepared baking sheet. Lightly spray the tops with cooking spray to help them brown.
Bake the chicken breasts in the preheated oven for 15 minutes.
Remove the baking sheet from the oven. Spoon 1/4 cup of marinara sauce evenly over each chicken breast.
Sprinkle 2 tablespoons of shredded mozzarella cheese evenly over the sauce on each chicken breast.
Return the baking sheet to the oven and bake for an additional 10 minutes, or until the chicken is cooked through (internal temperature of 165°F/74°C) and the cheese is melted and bubbly.
Remove from the oven and garnish each chicken breast with 1/2 tablespoon of chopped fresh basil leaves.
Serve immediately.