Now mix the celery leaves into the celeriac. Decant this mixture into a warm oven dish, and make eight indents in the surface of the mash, into which break eight eggs. Season the eggs and place two small knobs of butter on top. Bake in a hot oven for approximately 5 minutes, keeping an eye on it, until the egg whites are firmed up, but the yolks are still runny. Serve right away.