Mac'n Cheese Puffs

• 8 frankfurters
• 2 egg yoks
• 2 egg whites stiffly (beaten)
• 325 ml milk
• 220 gr soft bread crumbs
• 110 gr sharp cheddar (shredded)
• 50 gr macaroni
• 16 ml dijon mustard
• 14 gr butter
• 4 gr instant onion (minced)