First step is to make the pastry, If you have bought ready made shortcrust pastry then you can skip to step number 5 (6 if it is ready rolled).
Preheat the oven to 220℃.
In a large bowl, add the plain flour and diced butter. Use your fingers to rub it together until it resembles fine breadcrumbs. If you have a food processor then you can use the 'pulse' button to do this quickly.
Add one egg and mix well, tip the mixture out onto a clean surface and pat it together until a soft dough has formed.
Using a little flour, roll the dough out until it is roughly 3mm thick.
Place it into a 23 cm loose bottomed flan tin. Let the pastry fall into place, then press it into the edges. prick the bottom a few times with a fork then trim the edges, leaving a slight overhang in case the pastry shrinks. You can cut this later if necessary.
Place it into the fridge for 15 minutes. Then place a sheet of baking paper over the top and fill with baking beans.
Blind bake for 10 minutes, then remove the baking beans and bake for a further 10 minutes until the pastry is golden.
Turn the oven temperature down to 180℃.
In a frying pan add the bacon lardons, you don't need to add any oil, they will cook in its own fat. Fry until it has a nice colour to it. Then use a slotted spoon to remove the bacon and place it onto kitchen paper.
Add the diced onion and pepper into the pan and cook it in the bacon fat for 7-8 minutes until it has softened. Add the bacon back into the pan.
Spread the bacon, onions and peppers over the pastry base. Then grate half of the gruyere over the top.
In a mixing bowl, add the eggs and beat them lightly before adding the crème fraiche, double cream, chives and nutmeg. Mix well.
Pour the egg mixture into the pastry case until it reaches almost to the top of the pastry.
Grate the remaining gruyere over the top.
Bake in the oven for 25 minutes.
Leave it to settle for a few minutes before serving it warm Alternatively you can leave it to cool to room temperature and then store it in the fridge for up to 3 days.