Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally until cooked through but firm to the bite, about 8 minutes. Drain and return pasta to pot. Add butter, milk, and cheese mix to macaroni; stir until evenly mixed.

Stir eggs into macaroni and cheese until incorporated. Add 1 cup mozzarella cheese; stir until just combined.

Spread macaroni and cheese mixture into the prepared baking dish; top with pasta sauce. Sprinkle the remaining 2 cups mozzarella cheese over sauce. Cover the cheese layer with pepperoni and season with oregano.

Bake in the preheated oven until cheese is melted, about 30 minutes.