01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - Pound chicken breasts to even 1/2-inch thickness between sheets of plastic wrap. Season both sides with salt and pepper.
03 - Prepare three shallow bowls: flour in the first, eggs whisked with milk in the second, and breadcrumbs mixed with 1/2 cup Parmesan, garlic powder, and oregano in the third.
04 - Dredge each chicken breast in flour, shaking off excess. Dip in egg mixture, then coat thoroughly in breadcrumb mixture, pressing to adhere.
05 - Heat olive oil in a large skillet over medium heat. Fry chicken until golden and crisp, about 3 minutes per side. Transfer to prepared baking sheet.
06 - Spoon 2-3 tablespoons marinara sauce over each cutlet. Sprinkle with mozzarella and additional Parmesan.
07 - Bake for 15-18 minutes, until cheese is bubbly and chicken is cooked through (internal temperature reaches 165°F).
08 - Meanwhile, cook spaghetti in salted boiling water according to package directions until al dente. Drain well.
09 - Warm remaining marinara sauce in a saucepan over low heat. Toss with drained spaghetti.
10 - To serve, divide spaghetti among plates, top with chicken Parmesan, and garnish with basil if desired.