Preheat oven to 400 degrees and heat olive oil in a saucepan over medium heat. Add onion and garlic and sauté until translucent (about 3−4 mins).
Stir in crushed tomatoes, oregano, basil, parsley, sugar, salt and pepper. Once it reaches a boil, immediately reduce heat to low. Cover and simmer for 45 mins, stirring occasionally.
While sauce is simmering, rinse and trim chicken breasts and pound between sheets of plastic wrap or parchment paper to a width of ½". Cut flattened breasts into desired portion size and season both sides with salt and pepper then set aside.
Set up 4 plates for breading station. Place flour on 1st plate, beaten eggs on 2nd plate and a mix of breadcrumbs and ½ cup Parmesan cheese on the 3rd plate. Reserve the 4th plate to hold chicken once it is breaded.
Place one chicken cutlet into flour, turning to coat completely then pat cutlet to remove all excess flour. Then dip cutlet into beaten egg and turn to coat completely. Allow excess to drip off then place cutlet in the breadcrumb mixture, turn to cover both sides and press lightly to adhere breadcrumbs to chicken. Place the breaded cutlet on 4th plate until all cutlets have been breaded.
Heat ¼ cup extra virgin olive oil in large skillet over medium heat. Fry chicken cutlets until golden brown on both sides (3−4 minutes per side), working in batches if necessary, and set aside.
Coat bottom of 9" x 13" casserole dish with enough tomato sauce to cover completely then place fried chicken cutlets on top of sauce. Cover the chicken with remaining tomato sauce and sprinkle with chopped basil. Place a slice of mozzarella on top of each piece of chicken and sprinkle with Parmesan cheese.
Bake 12-15 minutes until cheese is melted and sauce is bubbly. Allow to rest 5 minutes before serving and enjoy!
You can bread the chicken up to a day in advance to save time!