Start by making the pastry. In a food processor add the flour, butter, egg yolk and water. Gently pulse until all mixed well. You may have to scrape the sides a couple of times.
Tip the mixture out onto a lightly floured surface. The mixture will be a little dry but this will all come together. Squish together to form a ball, turning and squishing a few times. Now using a floured rolling pin roll out as thin as you can.
Pre-heat the oven to 200 C / Gas 6. Very lightly grease a 23cm Pyrex fluted flan dish. Line the dish with the pastry and cut off the excess ensuring you come slightly above the dish to allow for shrinkage. (Reserve the excess pastry if needed for later.) Prick the base all over gently with a fork. Chill the dish in the fridge for 10 minutes. Put a baking tray in the oven.
Line the pastry with foil, shiny side down and fill with baking beans or rice and bake on the baking tray in the oven for 15 minutes.
Meanwhile, prepare the filling. Heat a small frying pan and dry fry the bacon over medium heat. Drain off any excess fat and continue to fry until the bacon starts to colour but do not let it become crisp. Remove onto kitchen roll to drain.
Finely dice 3/4 of the cheese. Grate the rest. In a mixing bowl beat the creme fraiche with a wooden spoon to loosen it. Add the cream in a steady stream and beat in. Mix in the beaten eggs and add the seasoning (go easy on the salt as the bacon is salty). Add the nutmeg and herbs.
Remove the flan dish from the oven and remove the beans or rice. Place back into the oven for a further 5 minutes.
Remove from the oven and add the bacon and diced cheese. Pour over the filling and finally sprinkle over the grated cheese.
Reduce the oven temperature to 190 C / Gas 5 and place the flan dish back on the baking tray. Bake for 25 to 35 minutes until set.
Remove from the oven and allow to cool.
Use reserved pastry to cover up any cracks after step 7 if needed.
I'm not entirely sure how many duck eggs would be needed for the recipe as I have not made with duck eggs before sorry I would not like to guess in case it does not turn out - this recipe is quite rich so adding duck eggs may make it too rich? Sorry I can't help further. - 14 Aug 2014