Creamy potato, leek and Gruyère tart

Method

1. Preheat the oven to 190°C/fan170°C/gas 5. Roll out the pastry to fit a 30cm x 20cm Swiss roll tin, with some pastry overhanging. Crimp the edges, prick the base and chill for 20 minutes.
2. Meanwhile, boil the potatoes for 7-8 minutes, until very tender. Drain and cool. Half-fill a pan with water, bring to the boil and cook the leeks for 2 minutes. Drain and pat dry.
3. In a large jug, beat the eggs with the crème fraîche, mustard, gruyère and garlic, then stir in the chives. Season well.
4. Line the pastry case with baking paper and fill with baking beans or rice. Bake for 15 minutes, until golden. Remove the baking beans and paper and bake for 2 minutes more.
5. Slice the potatoes into pound coin-thick slices and lay out on the pastry. Arrange the leeks on top of the potatoes and pour over the egg mixture. Bake for 20 minutes, until the filling has set and the top is golden. Stand for 10 minutes before serving. Also delicious served cold.