Preheat the oven to 375°F (190°C).
Place the chicken breasts between two sheets of plastic wrap and pound to an even thickness of about 1/2 inch.
In a shallow bowl, combine the flour with 1/4 teaspoon salt and 1/4 teaspoon black pepper.
In a second shallow bowl, beat the eggs.
In a third shallow bowl, mix the Italian-style breadcrumbs, grated Parmesan cheese, garlic powder, dried oregano, 1/4 teaspoon salt, and 1/4 teaspoon black pepper.
Dredge each chicken breast first in the flour mixture, shaking off excess, then dip into the beaten eggs, and finally coat evenly with the breadcrumb mixture, pressing gently to adhere.
Heat the olive oil in a large oven-safe skillet over medium heat. Add the breaded chicken breasts and cook for 3-4 minutes on each side until golden brown but not cooked through.
Remove the skillet from heat. Spoon marinara sauce evenly over each chicken breast.
Sprinkle shredded mozzarella cheese evenly on top of the sauce-covered chicken.
Cover the skillet tightly with aluminum foil and refrigerate for up to 24 hours if making ahead.
When ready to bake, preheat the oven to 375°F (190°C) if not already hot.
Bake the covered chicken parmesan for 20 minutes.
Remove the foil and continue baking for an additional 10-15 minutes until the cheese is melted, bubbly, and slightly golden.
Remove from the oven and sprinkle with chopped fresh basil before serving.