Chicken

Boil the potatoes until tender, drain and mash or pass through a ricer
Stir in the butter, cream and egg yolks into the mashed potatoes and set aside
Melt the butter in a large pan
Add the shallots, carrots and celery and gently fry until soft
Add the garlic, pour in the white wine and cook for 1 minute
Stir in the tomato purée, chopped tomatoes and stock and simmer until thickened
Add the shredded chicken, olives and parsley and season to taste
Preheat the oven to 350°F.
Put the filling in a 20x30cm ovenproof dish and top with the mashed potato
Grate the Gruyere over the potato
Bake for 30–35 minutes until piping hot and the potato is golden brown