Tart crustThis is rich and delicate without too much sweetness, and bakes crisp, so it's the perfect case for a jam filling.
225g plain flour, plus more for rolling
25g icing sugar
150g unsalted butter, softened
¼ tsp salt, or use salted butter
1 egg yolk
25ml cold water
Put the flour, icing sugar and butter in a bowl, add the salt and rub with your fingertips until the butter is worked through evenly. Add the yolk and water, and mix to a smooth, soft dough. Wrap, chill for 30 minutes to firm, then roll out to about 4-5mm thick for small, delicate tart cases, or slightly thicker for larger ones. Chill or freeze for 15 minutes to relax the dough slightly and minimise shrinkage while baking.
To blind bake small tart cases, take small squares of foil and place about a teaspoon of uncooked rice in each, pull up the foil and twist to seal in the rice and form a "knapsack" pastry weight. Place one in each lined pastry case, making sure there's a slight space around it to allow the pastry to puff slightly without sticking. This makes it easy to bake batches of tart cases without too much fuss. For larger tarts, press nonstick paper against the chilled pastry and weigh it down with rice, flour or baking beans.
To bake, go for a low temperature – 170C (150C fan-assisted)/335F/gas mark 3 – for 15-20 minutes with the blind baking weights in, then carefully remove the weights and bake until the base starts to colour lightly.
Scrape the remains of the jar in a saucepan with a little water and mash until smooth. Boil until the mixture reaches 104C, then spoon into the baked tart cases and leave to cool. Add chosen jam and await for the tart to set.