Preheat the oven to 160°C / 325°F / Gas Mark 3.
Divide the mixture into 8 and shape into round flat cakes and coat in breadcrumbs.
Cut around the tops of the peppers and remove the seeds with a teaspoon.
In a bowl mix together the breadcrumbs, chicken, spring onions, mushrooms and parsley. Season well.
Gently beat the egg yolks and combine with the stuffing mixture. (Add a little milk if the mixture is not moist enough).
Stuff the peppers with the mixture and place on a greased baking tray.
Bake in the oven for 30 minutes.