Flammekueche (Tarte Flambee)

Mix together the flour, oil, salt and water in a bowl. If it's too dry and won't come together, add a little more water, but it will be a relatively dry dough. Kneed for a minute then set aside while you prepare the toppings.

Preheat the oven to 450F/230C. Line a large baking sheet/tray (half sheet) with parchment.

Cut the bacon in to thin strips ('lardons') and cook in a small skillet/frying pan over a medium heat until they are just starting to brown. Remove from pan and set aside.

Add the onions to the pan, along with the butter, and cook a few minutes until the onions have softened but are only just browning.

Add the nutmeg, salt and pepper to the creme fraiche and mix well.

Roll the dough out on a lightly floured surface into a circle/oval as thin as you can (around ⅛in/3mm).

Transfer the dough to the lined baking sheet then spread the creme fraiche over the top, leaving a space around the edge without any topping.

Spread over the sauteed onions then top with the bacon, spreading them as evenly as you can. Top with the gruyere then bake for around 10 minutes until the edges are lightly brown and crisp and the toppings are just starting to color.