On flat surface cut a pocket in chicken breast leaving three sides intact. Stuff each breast with cheese and pepperoni. Press edges together to seal or use toothpicks if you choose.
In a 12 inch skillet, heat oil on med-high. Cook breasts for 8 minutes, turning occasionally until well browned on both sides. Remove breasts from skillet and set aside.
Slowly add water to skillet and increase heat to high. Bring to a boil, add macaroni, let cook for 4 minutes or until almost tender. Do not drain. Stir in spaghetti sauce until it boils. Return chicken to skillet, reduce heat to medium. Cover and simmer 10-12 minutes or until chicken juices from the center of the thickest breast comes out clear when cut. (170 degrees)
Garnish with extra pepperoni and cheese for a great mouthful of flavor.