In a food processor, grind the croutons until fine. Add to a bowl with the flour, half the salt, half the garlic powder, and parsley; mix well. Season the chicken with the remaining salt, garlic powder, and black pepper. Dredge breasts into the egg then crouton mixture. Allow the battered fillets to rest while the oil heats.
Preheat the oven to 400°. Add the olive oil to a cast iron skillet over medium heat. Fry the chicken on both sides until golden brown; add more olive oil if needed. Temp should be 165 degrees when done. In the same skillet, top the chicken fillets evenly with marinara and mozzarella. Place the skillet in the oven for 4-6 minutes to heat the sauce and melt the cheese. Serve immediately.