1Heat oven to 400°F. Line cookie sheet with cooking parchment paper. Unroll dough on cookie sheet; roll to 1/4-inch thickness. Brush dough with half of the oil. Bake 8 minutes.
2Brush partially baked crust with remaining oil. Top with onion, shredded cheese, sliced cheese and prosciutto. Sprinkle evenly with salt and pepper.
3Bake 10 minutes longer or until cheese is melted. Top with arugula. Cut into slices; serve immediately.