Peel and halve onions. Place in large saucepan in 2 inches of chicken broth. Bring to boil, cover and reduce heat. Simmer 20 minutes or until onions are tender but still firm; drain well. Gently lift out centers of onions, leaving shell 2 to 3 layers thick. Fill centers with peas. Combine bread crumbs, 5 tablespoons butter, Parmesan cheese, parsley and dry mustard. Sprinkle mixture over onions. Drizzle with melted butter. (To serve later, cover onions and chill.) Broil 5 to 7 minutes or until lightly browned. Garnish with pimiento strips.
This is a good make-ahead recipe.