01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
02 - Place chicken breasts between two sheets of plastic wrap and pound to an even thickness of 1/2 inch.
03 - Arrange three shallow dishes: place flour in the first, whisk eggs and milk in the second, and combine breadcrumbs, Parmesan, garlic powder, oregano, salt, and pepper in the third.
04 - Dredge each chicken breast in flour, shake off excess, dip into egg mixture, then coat thoroughly with breadcrumb mixture, pressing gently to adhere.
05 - Heat olive oil in a large skillet over medium-high heat. Fry chicken breasts 3 to 4 minutes per side until golden brown. Transfer to prepared baking sheet.
06 - Spoon 2 to 3 tablespoons marinara sauce over each piece of chicken, then evenly top with shredded mozzarella cheese.
07 - Bake in preheated oven for 15 to 18 minutes, until cheese is melted and bubbly and chicken reaches an internal temperature of 165°F.
08 - Bring a large pot of salted water to a boil. Cook spaghetti according to package instructions until al dente. Drain, then toss with olive oil and remaining marinara sauce.
09 - Serve spaghetti topped with a chicken breast. Garnish with fresh basil if desired.