Preheat the oven to 375°F (190°C).
Place the chicken breasts between two sheets of plastic wrap and pound them to an even thickness, about 1/2 inch thick.
Set up a breading station: In one shallow dish, place the flour. In a second dish, beat the eggs. In a third dish, combine the breadcrumbs, garlic powder, oregano, salt, and pepper.
Dredge each chicken breast in flour, shaking off the excess. Dip into the beaten eggs, then coat with the breadcrumb mixture, pressing gently to adhere.
In a large skillet, heat the olive oil over medium heat. Add the breaded chicken breasts and cook for about 4-5 minutes on each side, until golden brown.
Transfer the chicken to a baking dish. Spoon marinara sauce over each piece, then sprinkle with mozzarella and Parmesan cheese.
Bake in the preheated oven for 20-25 minutes, or until the cheese is bubbly and the chicken is cooked through (internal temperature should reach 165°F).
Remove from the oven and let it rest for a few minutes. Garnish with fresh basil leaves if desired.