Preheat oven to 200C/Gas Mark 6.
Roll out the pastry and use to line Pyrex Flan dish. Trim the excess and chill for 20 minutes. Line the pastry case with greaseproof paper and baking beans. Place the dish on a baking tray and "bake blind" for 10 minutes.
Remove from oven and reduce temperature to 190C/Gas Mark 5.
Melt the butter in a saucepan, then add the leeks. Fry for 5 minutes until soft, but without colour. Set aside to cool.
Cut the goats’ cheese into small pieces, and half the tomatoes. Beat the whole eggs and egg yolk together, then stir in the créme fraiche and dried chives. Season well with the salt and pepper.
Spread the leeks over the cooled pastry case, next add the goats cheese and cherry tomatoes. Pour the egg mixture evenly over the filling, and sprinkle with the parmesan.
Bake for 30-35 minutes, or until the filling is firm to the touch and golden brown on top. Allow to cool before popping in your lunch box