01 - Preheat the oven to 400°F and 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: flour in the first, whisked eggs with milk in the second, and a mixture of breadcrumbs, Parmesan, garlic powder, oregano, salt, and pepper in the third.
04 - Dredge each chicken breast in flour, shaking off excess. Dip into the egg mixture, then coat thoroughly with the breadcrumb mixture, pressing gently to adhere.
05 - Heat olive oil in a large skillet over medium-high heat. Fry chicken for 3 to 4 minutes per side until golden brown. Transfer to the prepared baking sheet.
06 - Spoon 2 to 3 tablespoons marinara sauce over each chicken breast, then top evenly with shredded mozzarella cheese.
07 - Bake in the oven for 15 to 18 minutes until cheese is melted and bubbly and the chicken reaches an internal temperature of 165°F.
08 - Bring a large pot of salted water to a boil and cook spaghetti according to package directions until al dente. Drain and toss with olive oil and 1 1/2 cups marinara sauce.
09 - Divide spaghetti among plates, place a chicken breast on top, and garnish with fresh basil if desired.