1.Preheat An Oven To 400 Degrees F (200 Degrees C). 2.Spread The Softened Cream Cheese On The Pre-Baked Crust. Sprinkle The Tuna And Onions Over The Pizza; Then Top With Shredded Mozzarella Cheese And Optional Red Pepper Flakes. Bake In Preheated Oven Until The Cheese Has Melted And Started To Brown, About 15 To 20 Minutes.