Preheat oven to 375°F. Line a baking sheet with foil; set aside. In a small bowl combine crumbled queso fresco, shredded part-skim mozzarella cheese, and finely chopped jarred pimiento.
Stuff sweet pepper halves with cheese mixture, mounding cheese mixture slightly. Sprinkle whole wheat panko on top of the cheese mixture. Lightly coat top of panko with nonstick cooking spray. Place peppers on prepared baking sheet. Bake 12 to 15 minutes or until golden brown on top.