Stir together chicken, mozzarella, olives, sun dried tomatoes, pepperoncini, and roasted red peppers.
Spray a large nonstick skillet with cooking spray (such as Pam) and place over medium-high heat. Divide Parmesan into 4 small piles (about 1 tablespoon each) spreading slightly. Top with 4 slices of bread.
Pile chicken mixture onto half the bread and cook for a minute or two until cheese is crusty. Close sandwiches and reduce heat ot medium. Cook for a minute or to two on each side or until bread is golden and filling is warm.