Slice the chicken breasts horizontally to create 6 fillets. Pound them with a meat mallet until about 1/2-inch thick for even cooking.
In a mixing bowl, whisk together 2 eggs, 1 tablespoon minced garlic, 2 tablespoons chopped parsley, and 1/4 teaspoon salt.
In another bowl, combine 1 cup Panko breadcrumbs, 1/2 cup Italian breadcrumbs, 1/2 cup grated Parmesan, 1 teaspoon garlic powder, and 1 teaspoon onion powder.
Dip each chicken fillet into the egg mixture, letting excess drip off, then coat evenly with the breadcrumb mixture, pressing to adhere.
Heat 1/2 cup olive oil in a large skillet over medium-high heat. Fry chicken fillets in batches for 4-5 minutes per side until golden and cooked through. Drain on paper towels.
In the same skillet, heat 1 tablespoon olive oil and sauté chopped onion until translucent. Add 2 teaspoons minced garlic and cook for 1 more minute.
Stir in 14 ounces tomato puree, 1/4 teaspoon salt, 1/4 teaspoon black pepper, 1 teaspoon dried Italian herbs, and 1 teaspoon sugar (optional). Simmer for about 10 minutes.
Preheat oven to 400°F (200°C). Spread a layer of marinara sauce in an oven-safe baking dish, place fried chicken on top, spoon more sauce over, then top with mozzarella and 1/3 cup Parmesan cheese.
Bake for 15-20 minutes until cheese is bubbly and golden.
Garnish with fresh basil or parsley before serving. Enjoy with pasta, salad, or crusty bread.