Heat oven to 350. Cook spaghetti to desired doneness in unsalted water as directed on pkg. Drain. Rinse with hot water. Lightly grease 12 x 8 inch or 9 x 13 inch baking pan.
In large bowl, lightly toss cooked spaghetti with milk and egg. Turn mixture into prepared baking dish. Spread evenly
Spoon sauce evenly over top; put pepperoni slices over sauce. Sprinkle with cheese. Bake at 350 for 30 to 40 minutes or until thoroughly heated and cheese is melted. Allow to cool 5 minutes before cutting into squares
. Tip: To make ahead, prepare, cover and refrigerate for up to 6 hours. Bake at 350 for 35 to 45 minutes. To reheat, cover loosely with foil. Heat at 350 for 15 to 20 minutes. Serves 9 to 12
Source: My Old Recipes