Working quickly, dip chicken pieces in egg white then breadcrumbs. Try to "push" crumbs and parsely on to chicken pieces - place into hot pan - add the remainder as quickly as possible.
Control heat - cook for no more than 3-4 minutes each side.
Remove cooked chicken to a hot plate.
Crush capers and seeded mustard in mortar - make a sorta paste.
Pour paste into hot pan with about 3 tbls butter and scrape / stir quickly for no more than a minute.
Plate the chicken - add the caper/mustard/ butter sauce over the chicken.
Best, quickest and most piquant chicken you have ever tasted!!