Preheat oven to 450 degrees F. Lightly coat a baking sheet or pizza pan with olive oil.
In a large bowl, combine artichoke hearts, spinach, sour cream, cream cheese, mayonnaise, garlic powder and onion powder; season with salt and pepper, to taste. Stir in 1/4 cup mozzarella cheese and Parmesan; set aside.
Working on a surface that has been sprinkled with cornmeal, roll out the pizza into a 12-inch-diameter round. Transfer to prepared baking sheet or pizza pan.
Spread artichoke mixture evenly over the pizza; top with remaining 3/4 cup mozzarella cheese.
Place into oven and bake for 15-20 minutes, or until the crust is golden brown and the cheeses have melted.
Serve immediately, garnished with parsley, if desired.