01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - Pound chicken breasts to an even thickness of about ½ inch. Season with salt and pepper.
03 - Prepare three shallow bowls: Bowl 1 with flour, Bowl 2 with whisked eggs and milk, Bowl 3 with breadcrumbs mixed with ½ cup Parmesan, oregano, and garlic powder.
04 - Dredge each chicken breast in flour, shake off excess, dip in egg mixture, then coat thoroughly with breadcrumb mixture.
05 - Heat olive oil in a large skillet over medium heat. Fry chicken breasts 3–4 minutes per side until golden brown. Transfer to prepared baking sheet.
06 - Top each chicken breast with marinara sauce, then sprinkle with mozzarella and additional ¼ cup Parmesan cheese.
07 - Bake for 15–18 minutes until cheese is melted and chicken reaches internal temperature of 165°F.
08 - Heat olive oil in a saucepan over medium heat. Sauté onion 3–4 minutes until soft. Add garlic and cook 1 minute.
09 - Stir in crushed tomatoes, basil, oregano, sugar, salt, and pepper. Simmer uncovered for 15–20 minutes, stirring occasionally. Stir in fresh basil if using and adjust seasoning.
10 - Cook spaghetti in salted boiling water according to package instructions. Drain and toss with half of the marinara sauce.
11 - Serve breaded chicken over a bed of spaghetti marinara. Spoon extra sauce on top and garnish with additional Parmesan and fresh basil if desired.