Bring a large pot of lightly salted water to a boil. Add penne and cook, stirring occasionally, until tender yet firm to the bite, about 11 minutes. Drain and run under cold water to stop cooking process. Drain again.

Mix together 2/3 of the mozzarella cheese, mayonnaise, pepperoni, olives, green onions, parsley, vinegar, mustard powder, Italian seasoning, pepper, and salt in a large bowl. Add pasta and toss until coated. Sprinkle remaining mozzarella and paprika on top. Refrigerate 1 1/2 hours before serving.