In a bowl, whisk together eggs, buttermilk, garlic powder, kosher salt, and pepper.
Place chicken slices into the egg mixture, ensuring they are well-coated. Let them marinate for at least 30 minutes.
In a shallow dish, combine flour, cornstarch, kosher salt, pepper, oregano, garlic powder, and cayenne pepper.
Dredge each marinated chicken slice in the flour mixture, ensuring an even coating.
Dip the floured chicken into the Panko breadcrumbs, pressing gently to adhere the crumbs.
Heat 1 inch of vegetable oil in a pan over medium-high heat.
Fry breaded chicken until golden brown and cooked through, about 3-4 minutes per side. Place on a paper towel-lined plate to drain excess oil.
In a saucepan, combine marinara sauce, diced tomatoes, kosher salt, oregano, garlic powder, and dried basil. Simmer for 15-20 minutes, allowing flavors to meld.
Stir in fresh basil before serving (if using).
Cook spaghetti in a large pot of salted boiling water until al dente. Drain and set aside.
Preheat the broiler.
In a baking dish, spread a layer of the prepared sauce. Place the fried chicken on top.
Spoon additional sauce over each piece of chicken, then sprinkle with parmesan and mozzarella cheese.
Place the baking dish under the broiler until the cheese is melted and bubbly, about 2-3 minutes. Keep a close eye to prevent burning.
Serve the chicken Parmesan over the cooked pasta, with extra sauce if desired.
Garnish with additional fresh basil and a sprinkle of parmesan cheese before serving.