Prepare Ahead:

Refrigerate the cooled, baked quiche for up to 2 days; reheat at 325°F (160°C) for 15–20 minutes.

1. To make the dough, pulse the flour and butter in a food processor until the mixture resembles fine crumbs. Mix the yolk and water. Transfer the flour mixture to a bowl and stir in enough of the water mixture until the dough clumps together. Gather in a disk and wrap in plastic wrap. Refrigerate 30 minutes. On a lightly floured surface, roll out the dough 1/8 in (3mm) thick. Line a 9in (23cm) tart pan with a removable bottom with the dough, trimming any excess. Refrigerate for 30 minutes.

2. Preheat the oven to 375°F (190°C). Prick the dough with a fork, and line with parchment paper and beans. Place on a baking sheet and bake 15 minutes. Remove the parchment paper and beans and bake another 10 minutes, until golden.

3. Meanwhile, cook the bacon in a large frying pan over medium heat about 4 minutes, until golden. Add the onion and cook 2–3 minutes, until softened. Spread in the pastry shell, then sprinkle with the Gruyére.

4. Whisk together the eggs, cream, milk, and season with pepper. Pour into the shell. Bake for 25–30 minutes, or until golden and just set. Serve hot, warm, or cold.

VARIATION

Mushroom Quiche:

Omit the onion, bacon, and Gruyére. Cook 1 large red onion, finely chopped, with 2 tbsp olive oil in a pan over medium heat for 2–3 minutes. Add 10oz (300g) of sliced mixed mushrooms and 1 minced garlic clove. Cook for another 6 minutes. Spoon into the pastry and sprinkle with 4 tbsp freshly grated Parmesan cheese and 3 tbsp chopped parsley. Add the custard and bake as above.