Marinate the Chicken: Place the chicken breasts in a large bowl and pour in the buttermilk, ensuring that all pieces are fully submerged. Cover the bowl and refrigerate for at least 1 hour, or preferably overnight.
Prepare the Dredging Station: In the first dish, combine the all-purpose flour, grated Parmesan cheese, garlic powder, onion powder, paprika, salt, and black pepper. In the second dish, beat the eggs. Fill the third dish with the breadcrumbs.
Dredge the Chicken: Remove each chicken breast from the buttermilk and coat it in the flour mixture, then dip it into the beaten eggs, and finally press it into the breadcrumbs.
Heat the Oil: In a large skillet, pour in the olive oil and heat it over medium heat until it shimmers.
Cook the Chicken: Add the breaded chicken breasts to the skillet and cook for approximately 5-6 minutes on each side until golden brown and the internal temperature reaches 165°F (75°C).
Drain and Rest: Transfer the chicken to a plate lined with paper towels to drain excess oil and let it rest for a few minutes.
Serve: Present the Parmesan chicken hot, with marinara sauce on top if desired, and garnish with freshly chopped parsley.