Preheat the oven to 425F and then use a meat tenderizer to pound the chicken breasts into 1 inch thickness.
To make the rub mix the olive oil, lemon juice, oregano, paprika, cumin, mustard powder, salt, and pepper together.
Cover the chicken breasts in the rub spread it to coat the whole breast.
Lay the chicken into a casserole dish or onto a baking tray lined with parchment paper. Place the dish into the heated oven to bake for 15 minutes, or until the internal temperature reads 165F.