Lettuce, spring onion and cheese tart

SERVES 4–6
FOR THE PASTRY
250g plain flour
A pinch of sea salt
125g chilled unsalted butter,
cut into small cubes
About 75ml cold milk
FOR THE FILLING
1 tablespoon rapeseed
or olive oil
4 Little Gem lettuce hearts, trimmed and quartered
15g butter
2 bunches of spring onions (about 250g), trimmed and cut into chunky slices
100g Lancashire, medium Cheddar or hard goat’s cheese
2 large eggs, plus 2 extra egg yolks
200ml double cream
200ml whole milk
Sea salt and freshly ground
black pepper
To make the pastry, sift the flour and salt together, or give them a quick blitz in a food processor. Add the butter and rub in with your fingertips, or blitz in the food processor, until the mixture resembles fine breadcrumbs. Mix in the cold milk, little by little, until the pastry just comes together, then turn out onto a work surface and knead briefly to bring it into a ball. Wrap and chill for 30 minutes.
Preheat the oven to 180°C/Gas Mark 4. On a lightly floured surface, roll out the pastry quite thinly and use to line a 25cm tart tin. Leave the rough edges of the pastry hanging over the sides of the tin. Line with foil and baking beans and bake blind for 15 minutes. Remove the foil and beans, prick the pastry in a few places with a sharp fork, and bake uncovered for a further 10–15 minutes, or until the pastry is just starting to colour. Using a small, sharp knife, trim away the excess pastry from the edge.
To make the filling, heat the oil in a frying pan over a medium heat. Add the quartered lettuce hearts, sprinkle with salt and pepper and cook for about 5 minutes, turning once or twice, until the cut surfaces are golden brown. Add the butter towards the end of cooking, letting it melt in the pan, then spooning it over the lettuces. Using a slotted spoon, remove the seared, buttery lettuce hearts and arrange in the pastry case.
Reduce the heat under the frying pan a little. Add the spring onions and sauté gently for 5 minutes, then scatter in the tart case over and around the lettuce hearts. Crumble or grate the cheese over the top.
Lightly beat the eggs, egg yolks, cream and milk together in a bowl and season generously with salt and pepper. Carefully pour this mixture over the tart filling (depending on the depth of your tin, you might not need all of it). Bake for about 35 minutes until golden. Serve warm or at room temperature.