Whisk the egg whites with cream in a bowl. Add the breadcrumbs until well-combined then set aside.
Blend the cod pieces in a blender then add to the egg mix. Season with celery salt and pepper then stir until well-combined. Refrigerate for 30 minutes.
Melt the butter over medium heat in a non-stick pan then cook up the leek, carrot and celery for 5 minutes. Add the flour and stir for 2 minutes.
Combine the white wine, milk and clam juice then pour over the vegetables while whisking continuously. Simmer over low heat for 10 minutes. Add the laurel leaves, tarragon and parsley then season.
Shape 1” balls and add to the tarragon sauce delicately. Cover and simmer over low heat for 20 minutes. Check the seasoning if needed then serve.