Leek, comté and thyme quiche

Method

1. Put the flour and 150g of the butter in a food processor and pulse until the mix resembles breadcrumbs (you can also do this with your fingers in a large mixing bowl). Crack in one of the eggs, add 2 tbsp cold water, then pulse or mix until it forms a ball of dough. Transfer to a floured surface, bring together, then roll out into a large circle, around 27cm in diameter and 0.5cm thick. Transfer to the tart tin and gently press it into the edges. Cut off any excess and prick the case all over with a fork. Put the pastry case in the fridge to firm up for 30 minutes.
2. While the pastry is chilling, finely slice the leeks and put in a large frying pan with the remaining 25g butter and the olive oil. Add the thyme leaves, season well and cook over a low-medium heat for 20-25 minutes, stirring frequently, until soft and sticky. Add a splash of water while cooking if the leeks are catching. Leave to cool.
3. When ready to bake the tart, heat the oven to 180°C fan/ gas 6. Fill the lined tart tin with baking paper and baking beans (or uncooked rice). Bake for 12 minutes, then remove the paper and beans/rice and bake for 12-15 minutes more until lightly golden. Meanwhile, in a mixing bowl, whisk the single cream, milk and remaining eggs with a good pinch of salt and pepper until smooth. Stir in the grated cheeses and cooled leeks.
4. When the case is ready, put it on a baking sheet to make it easier to manoeuvre. Pour in the cheese filling. At this point you can freeze the quiche (see Make Ahead) or bake for 30 minutes until just set. Remove from the oven and leave to cool in the tin, then either freeze (see Make Ahead) or remove and serve.