Preparation of the marinara sauce:
Heat the olive oil on medium heat in a pot on the stove. Braise the onions and garlic for about 2-3 min. or until softened. Add the carrots and celery and season with salt and black pepper.
Fry for about 5 min. Add the tomato sauce, basil and bay leaves and let it simmer on low heat until it thickens. Once ready, take the bay leaves out and try the sauce. If the sauce has a slightly sour taste (because of the tomatoes), add a little cold butter. Once the tomato sauce cools - blend it.
Preparation of the Chicken Parmigiana:
Mix the olive oil with the herbs. Season with salt and pepper. Smear the chicken fillets with the seasoned olive oil. Heat the pan on high heat. Crisp the chicken fillets 2 min. per side.
Place the chicken fillets in an oven dish and pour the marinara sauce over them. Cut the mozzarella into slices and put them on top of the chicken fillets. Sprinkle with several tablespoons parmesan and put a few lumps of butter on the fillets.
Bake the dish for about 15 min. in a preheated 392°F (200 °C) oven or until ready.