1. Preheat oven to 400˚. Line a baking sheet with silicone mat, parchment paper or foil sprayed with nonstick cooking spray. Set aside.
2. In a shallow bowl combine the mustard, Cracked Black Pepper Rub, and water.
3. In a second shallow bowl combine the panko, olive oil, and parsley.
4. Starting at the thicker side, make a lengthwise horizontal cut into the top two-thirds of a chicken breast, stopping before cutting all the way through. Fold it open like a book. (The chicken breast should still be in one piece.) Put the breast between two pieces of plastic wrap and pound it out on both sides with the flat side of a meat tenderizer (a rolling pin or heavy pan) working from the inside out, until it’s spread to double its original size and about 1/4 inch thick. Repeat with the remaining breasts.
5. Dredge each chicken breast into the mustard mixture, and then into the bread crumb mixture. Pat the crumbs on to make sure they adhere. Place onto the prepared pan.
6. Bake for 25 to 30 minutes or until internal temperature reaches 160º. Serve warm.