Preheat oven to 400 degrees F (200 degrees C).
Cook Pizza Sauce (1 jar) in pan on low heat to reduce for about 10 minutes. This will keep the sauce from becoming watery in the pan when you bake it.
Meanwhile, butterfly the Chicken Breast (3) and cut into 2 pieces. Then, pound chicken breasts.
Mix Salt (1 teaspoon), Ground Black Pepper (1 teaspoon), and Fresh Oregano (1 teaspoon) together. Sprinkle each breast with the seasoning.
Heat the Olive Oil (1 tablespoon) in a nonstick pan. Cook chicken breasts on each side for 1 minute, just enough to brown the outsides to lock in their juice.
Lay chicken breasts in a 9x13-inch baking dish, and spread all of the sauce on each of the chicken breasts. Then top with Shredded Mozzarella Cheese (8 ounce) and then Pepperoni Slice (6 ounce).
Bake for 25 to 30 minutes.
Rest for 5 minutes then serve.