Preheat oven to 400.
Slice chicken breast through the middle to make four thinner breast pieces.
Slather mayonnaise on both sides of the chicken.
Mix Panko, parmesan cheese, salt, pepper in a large flat dish or plate.
Dredge both sides of the chicken breasts through the bread crumb mixture pressing down to cover the entire breast.
Place the four breasts on a parchment paper-covered cooking sheet and back for 25-30 minutes until golden brown. Watch carefully so the parmesan coating doesn't burn.
Remove the chicken from the oven and spoon 1 -2 tablespoons of the prepared marinara sauce on each breast.
Set the oven to broil.
Top each breast with 2 slices of mozzarella cheese.
Broil for 2-3 minutes, watching carefully, until cheese is melted.