Leftover Mac & Cheese Pizza Skillet

2 c. leftover Macaroni & Cheese
2 Tbs. Cooking Oil
8 oz. (1 c.) Pizza Sauce or Spaghetti Sauce
1 c. Shredded Mozzarella Cheese
Pepperoni

Coat bottom of skillet with oil. Cover bottom of skillet with leftover mac & cheese. Pour sauce evenly over the top. Layer cheese over all and add pepperoni slices. Cover with lid and cook over low heat until heated through and cheese has melted.