In a large mixing bowl whisk the salt into the flour then tip in the butter. Rub between your fingertips until the mixture resembles course breadcrumbs.
Add the egg and cold water and bring together with your hands to form a smooth dough which shouldn’t be sticky. Wrap in cling film and place in the fridge for half an hour to rest.
In a medium sized saucepan heat the olive oil then add the pancetta and onions and cook on a low to medium heat for about 15 minutes until the pancetta has begun to crisp up and the onions have caramelised. Remove from the heat and leave to cool to room temperature.
Roll the pastry out on a floured surface to about 3mm thickness and cut out into 4 inch rounds
Press the pastry circles lightly into a 12 hole and 6 hole muffin tin and place back into the fridge for a further half hour.
In a large mixing bowl whisk the eggs and egg yolks with the crème fraiche. Add the gruyère, nutmeg and salt and pepper and mix until fully combined then stir in the bacon and onions.
Pour the filling evenly into the pastry cases then place in the oven.
Bake for 10 minutes at 180°C, then turn the heat down to 160°C and bake for a further 10 minutes.
Remove the tartlets from the oven and leave in the tins for about 5 minutes to settle then lift out to finish cooling on a wire rack.
*For the Gluten-Free Pastry 80 g rice flour 25 g oat flour 45 g buckwheat flour 30 g cornflour 15 g tapioca starch 15 g ground chia seeds ½ teaspoon sea salt 115 g cold unsalted butter cut into very thin slices 1 egg medium, lightly beaten 2-4 tablespoons iced water 2 tablespoons gluten-free flour for rolling out
In a large mixing bowl combine the flours, chia seeds and salt.
Rub the butter into the flour in between your fingertips so it resembles very rough breadcrumbs then stir in the beaten egg with a fork.
Add the water 1 tablespoon at a time and start to bring the dough together with a pastry scraper. It should start to form quite quickly.
Tip the dough onto the work surface and quickly bring the ball into a round ball with your hands. You don’t really need to work the pastry as there’s no gluten to activate. The pastry should still be a little sticky.
Wrap the pastry ball in greaseproof paper and flatten it slightly.
Place in the fridge for 30 minutes to rest. Then continue as per the rest of the recipe above.