Servings: 8

Filling: subheading: Filling:
100g unsalted butter, chopped 100g unsalted butter, chopped
2 tablespoons extra-virgin olive oil 2 tablespoons extra-virgin olive oil
2 medium leeks, finely sliced 2 medium leeks, finely sliced
2 onions, finely sliced 2 onions, finely sliced
1 teaspoon sea salt flakes 1 teaspoon sea salt flakes
2 tablespoons chopped fresh thyme leaves 2 tablespoons chopped fresh thyme leaves
150g comté or other hard melting cheese, grated 150g comté or other hard melting cheese, grated
4 eggs, lightly beaten 4 eggs, lightly beaten
250ml single cream 250ml single cream
Handful of watercress to serve Handful of watercress to serve
Pastry: subheading: Pastry:
250g plain flower 250g plain flower
100g cold unsalted butter, chopped 100g cold unsalted butter, chopped
1 egg yolk 1 egg yolk
1 tablespoon cider vinegar 1 tablespoon cider vinegar

Pastry: subheading: Pastry:
Put the plain flour and a pinch of salt in a large mixing bowl. Using your fingers, rub in the butter until the mixture resembles coarse bread crumbs. Add the egg yolk. Chill the vinegar and 60 ml water in a jug with 4 ice cubes. Remove the ice cubes, then use your fingers to mix the liquid gently into the flour mixture and bring it together into a shaggy dough. Wrap well, then chill for 2 hours.
Filling: subheading: Filling:
Melt the butter and oil together in a medium non-stick frying pan over a low-medium heat. Add the leeks, onions, and 1 teaspoon sea salt flakes, then cook, stirring occasionally, for 30 minutes or until the onions and leeks are soft and lightly caramelised. Stir in the thyme leaves and season with freshly ground pepper. Set aside to cool to room temperature.
Heat the oven to 200°C/180°C Fan/Gas 6. Roll out the chilled pastry on a lightly floured work surface to 3 mm thick, then line the fluted tin, trimming the excess with a sharp knife, and prick the base all over with a fork. Line the pastry with compostable baking paper, then fill with ceramic baking beans or uncooked rice. Blind bake for 25 minutes or until the pastry is light golden. Remove the baking beans/rice and paper (if using rice, save it for future blind baking), then bake for a further 10 to 15 minutes or until the base is cooked and feels sandy to the touch.
Reduce the oven temperature to 160°C/140°C fan/gas 3. Put the leek and onion mix in a bowl with the grated cheese, eggs, cream and some salt and pepper. Mix, then pour into the pastry case. Bake for 35 to 40 minutes until the mixture feels just set to the touch. Cool to room temperature, then scatter with the watercress and some black pepper. Serve the quiche warm from the oven or at room temperature.