Marinara Sauce: Heat 1 tbsp extra virgin olive oil in a large pan over medium heat. Add in onion and fry until it begins to soften/brown, then add in garlic and fry for 1-2mins more. Pour in passata and swill the jar/carton with a splash of water. Add basil and oregano, then add a pinch of sugar, salt and pepper (all to taste). Give it a stir then turn heat to low and gently simmer for 20-25mins, or until it's nice and thick. This is important to intensify the flavour and reduce down the sauce.
Pound Chicken: Add chicken breast to a chopping board, lay over cling film and pinch around the edges (to prevent moisture from escaping). Bash with a rolling pin, mallet or heavy pan until even thickness. You want it fairly thin, but not so much it begins to break apart. Around 1/2" is fine.
Chicken Seasoning: In a small pot combine 1 tsp salt and garlic powder, alongside 3/4 tsp dried oregano and 1/2 tsp black pepper.
Dredge Chicken: Line up 3 bowls - the first is flour with half the chicken seasoning stirred in, the 2nd is 2 beaten eggs and the 3rd is Panko, parmesan and the rest of your seasoning. Coat the chicken in the flour, then into the egg and finish with a coating of the parmesan panko. Ensure the chicken is thoroughly coated at each stage, especially in the Panko.
Fry Chicken (see notes for baking option): Heat up 1 cup oil over medium heat in a large skillet, or enough to cover around half the chicken. You want the oil around 350F/180C (drop a few crumbs in to test if they rapidly bubble). Carefully place chicken in 2 breasts at a time and fry for 4-5mins on each side, or until golden on the outside and white through the centre.
Chicken Sandwich: Place fried chicken on top of the bottom ciabatta halves. Spread over a few dollops of marinara sauce, then top with mozzarella and finish with a pinch of parmesan. Place under the grill and broil until golden/gooey.
Serve: Sprinkle over fresh basil, then add the second ciabatta half and tuck in. Use leftover marinara sauce as a dip (optional).