In large bowl or food processor, blend first 7 ingredients until smooth. Saut ' onions in remaining butter until soft and transparent. Add onions and shrimp to potato mixture, blend thoroughly. To form balls, drop 15 ml. Chill covered at least 1 hour.
Drop balls into egg mixture.
Re-roll in crumbs. Drain on paper towel. Serve immediately or chill and reheat thoroughly 20 min.