Place the butter, garlic and parsley into a small bowl with a good pinch of salt. Mix well then shape into a sausage shape then tightly wrap and chill until really firm.
Slice into 8 even pieces. Use a sharp knife to make a deep pocket inside each chicken breast. Fill with two pieces of garlic butter and re-seal with your hands. Put the flour on one plate, the eggs onto another and the breadcrumbs on a third plate.
Dip each breast in the flour, then the egg and finally the breadcrumbs. Chill well.
Fry in plenty of oil for 4-5 on each side then build your burger.