1. Preheat oven to 450°.
2. Heat oil in a large nonstick skillet over medium-high heat. Add onion to pan; cover and cook for 3 minutes. Uncover and cook 10 minutes or until golden brown, stirring frequently.
3. Place pizza crust on a baking sheet. Top evenly with onion mixture; sprinkle with cheese. Top evenly with pear and prosciutto. Sprinkle with pepper. Bake at 450° for 12 minutes or until cheese melts. Sprinkle with nuts. Place arugula in a medium bowl. Drizzle vinegar over greens; toss gently to coat. Top pizza evenly with arugula mixture. Cut pizza into 8 wedges.