Preheat oven to 375 degrees. Spray a 9×13 baking pan with non-stick spray. Set aside.
Rinse chicken with water, and pat dry. Trim off any visible fat. Cut a deep, horizontal pocket in each piece of chicken. (Be careful not to cut all the way through) Stuff each chicken breast with one slice of Mozzarella cheese and 4 pepperoni slices. Sprinkle the tops of pepperonis with a dash of dried basil and garlic powder. Close the chicken breasts, and secure with a toothpick.
Spread the bread crumbs in a shallow dish or plate. Dredge each breast into the bread crumbs to coat lightly. Place all the coated and stuffed chicken breasts into the baking pan.
Bake for 30-35 minutes, or until chicken is thoroughly cooked. Remove pan from oven, and then remove the toothpicks from each chicken breast. Pour about 1/4 cup of marinara over each chicken breast. Sprinkle with shredded mozzarella and parmesan cheese. Place back in oven and bake another 5 minutes, or until cheese is melted and bubbly.