First make the pastry. Combine both flours in a large mixing bowl and cut both cold fats into small cubes. Add to the flour and rub in thoroughly (to the texture of breadcrumbs). See our rubbing in & dough Tip. Add enough cold water to form a dough (start with 2 tablespoons); stir to combine, then bring the dough together into a ball with your hands. Remove onto a floured surface and knead gently. Wrap in cling film or a plastic bag and chill in the fridge for about 10 to 20 minutes. While the dough is chilling, prepare the filling. Pre-heat your oven to 200C (180C fan).
Remove the ends from the leeks and slice down the length to the centre. Remove the outer few leaves, then cut into rounds. Remove any dirt as you go. Separate the rounds of leek, and wash the pieces in a colander or large sieve.
Gently fry the leeks in the butter and a little oil until soft, then add cayenne pepper to taste and a large grating of fresh nutmeg. Season with salt, and black pepper if required, bearing in mind the cayenne is hot. Set aside to cool.
Coarsely grate the cheese. Pour the carton of sour cream into a jug and make the total measurement up to half a pint (about 300ml) with single cream or milk. Whip up the eggs with the cream mixture in a jug to combine. See our egg Tip. Grease the tart tin very lightly; a loose bottomed one is best. Remove the pastry from the fridge and knead briefly on a floured surface, before rolling to size to fit the tin. Line the tin with pastry, taking care as the pastry is very short and may break. If it does, you can patch it in the tin. See our rolling & lining Tip. Cover with cling film and return the pastry-lined tin to the fridge for at least another 30 minutes, or more. If you wish to blind bake the tart case you can do so now. This will give a better result, but it isn’t 100% necessary. If you do, line the pastry case with baking paper & baking beans/weights, and bake for about 10 minutes. Then remove the paper & beans and bake for about another 5 minutes to dry the pastry out. See our blind baking Tip. Now assemble the leek quiche. Place half the grated cheese evenly in the base of the lined tin, cover with the cooled leeks, then add the rest of the cheese in an even layer. Sieve in the egg mixture and shake the tin gently to ensure it is evenly distributed.
Bake in the heated oven for 30-40 mins until fully set and golden on top. If it is colouring too fast, particularly the top edge of the pastry which can colour up before the filling is set, cover the top of the tart loosely with foil.
The tart can be eaten hot or cold, but is probably nicest just warm. Serve with a salad - or also with new potatoes if really hungry.
Enjoy!
