Cut the chicken in half (or butterfly it) and pat it with paper towels.
Season each breast with salt and garlic powder on both sides.
Spread a thin layer of mayo on both sides of the chicken.
Pour the Panko bread crumbs into a shallow bowl. Coat each chicken breast in Panko bread crumbs. Make sure to press the chicken into the bread crumbs to coat it completely.
Heat a large nonstick pan over medium heat. Add 2 tbsp of olive oil and pan-fry until golden brown. There is no need to cook the chicken all the way through—just make the Panko crumbs golden.
Transfer the chicken to a foil-lined baking sheet. Don't skip the foil! It's great not having things stuck to the baking sheet. Trust me!
Spoon the marinara sauce over the chicken, then add the mozzarella cheese and the Parmesan cheese.
Bake it in the oven until the cheese melts and turns golden brown and until the chicken is cooked through (about 10 minutes).