Heat 2 tablespoons olive oil in a medium saucepan over medium heat. Add the minced garlic and red pepper flakes, if using, and cook for about 1 minute until fragrant but not browned.
Pour in the crushed tomatoes and add 1/2 teaspoon kosher salt. Simmer gently, uncovered, for 12 to 15 minutes until slightly thickened. Stir in the torn basil, remove from heat, and set aside.
Slice each chicken breast in half horizontally to create 6 thin cutlets. Place each between two sheets of plastic wrap and pound to an even 1/4 inch (6 mm) thickness.
Pat both sides of every cutlet completely dry with paper towels, then season all over with 1 teaspoon kosher salt and 1/2 teaspoon black pepper.
Set up three shallow bowls: flour in the first, beaten eggs in the second, and a mixture of panko, 3/4 cup Parmesan, garlic powder, Italian seasoning, and 1/2 teaspoon black pepper in the third.
Working one cutlet at a time, dredge in flour and shake off excess, dip into the beaten egg letting extra drip off, then press firmly into the panko-Parmesan mixture, coating both sides. Set aside and repeat with all 6 cutlets.
Heat 1/2 cup olive oil in a large cast iron skillet over medium-high heat until it shimmers. Fry 2 or 3 cutlets at a time for 2 to 3 minutes per side until deeply golden and crisp, then transfer to a wire rack. Add more oil as needed between batches.
Preheat oven to 425°F (220°C). Spread about 1/2 cup marinara across the bottom of a 3-quart baking dish and arrange the fried cutlets in a single layer on top.
Spoon 2 to 3 tablespoons of sauce over the center of each cutlet, leaving the crisp edges exposed. Top each with sliced mozzarella and a sprinkle of the 1/3 cup grated Parmesan.
Bake for 10 to 12 minutes until the cheese is fully melted and bubbling. For golden, blistered cheese, broil for the last 1 to 2 minutes and watch closely.
Confirm the chicken has reached 165°F (74°C) in the thickest part with an instant-read thermometer. Garnish with fresh basil and serve right away over pasta or with your favorite sides.