Heat oven to 400°F. Boil spaghetti with tablespoon salt to 2 minutes short of package time. Drain; toss with 1 tablespoon oil and spread in large bowl to cool 5 minutes.
Beat eggs with Parmesan; thoroughly toss through warm, not steaming, noodles. Grease 9-by-13-inch metal pan with remaining oil; press spaghetti into even base.
Bake base 12 minutes until starting to set. Mix sauce, oregano, and garlic powder.
Spread sauce over base; add mozzarella, pepperoni, and olives. Bake 15 to 18 minutes until topping bubbles and center 165°F.
Rest 10 minutes; cut 8 squares with wide spatula.