Fill large saucepan 2/3 full of water. Heat to boiling. Stir in contents of Pasta.
Gently boil uncovered 15 minutes, stirring occasionally, until tender.
Drain pasta. Rinse with cold water. Shake to drain well.
Combine Hidden valley ranch mix, onion powder and bacon bits with mayonnaise in large bowl. Stir in chilled pasta and remaining ingredients except lettuce. Serve on lettuce. Refrigerate leftovers (if desired, moisten with a few teaspoons milk before servings).