This shortcut version of the irresistible French patisserie-style fruit tart uses bought puff pastry.
First make the custard. Stir the custard powder and caster sugar together in a small pan. Slowly pour in the milk, stirring with a wooden spoon as you go to keep it smooth. Heat through, stirring all the time – it will soon become very thick. Once the custard comes to the boil, lower the heat and simmer for 1 minute. Remove from the heat, spoon the custard into a small bowl and lay a piece of clingfilm over the surface to prevent a skin from forming. Leave to cool.
Meanwhile roll out the puff pastry on a lightly floured surface, to a thickness of about 2–3mm.
Cut out four 14cm circles, using an upturned bowl as your guide. You should get three circles out of the first rolling, then gather together and re-roll the pastry trimmings so you have enough pastry to cut out the fourth.
Lay the 9–10cm flan cases on a baking sheet. Line the cases with the pastry circles, easing the pastry into the corners of the tins and creating small folds to make them fit well (the folds all add to the quirky character of the tarts). Lightly prick the base of each pastry case with a fork then chill them in the fridge for 20 minutes. Pre-heat the oven to 220°C/200°C fan/425°F/Gas 7.
Line each pastry case with a circle of baking paper and fill with baking beans or rice. Blind bake the pastry for 10 minutes, or until the pastry is set, then remove the paper and beans or rice. Re-prick the pastry cases with a fork if it looks like they have risen, and return to the oven for another 5–8 minutes, or until they are a pale golden colour. Remove and set aside. If the pastry cases are at all puffy, press them down so that there is plenty of room for the filling.
Now your cases are ready to fill. Once the custard is cool, stir in the 4 tablespoons of ground almonds, ¼ teaspoon of almond extract and 4 tablespoons of crème fraiche. Spoon an equal amount of the almond custard into each pastry case and level it off.
Halve, stone and thinly slice the 3 nectarines and then arrange the slices on top of each tart by standing them upright, skin side at the top, and overlapping and bending them to make a tight circle all around the inside edge. Do two or three more circles in the same way until you reach the centre. If you have a gap in the middle, fill it with small nectarine slices. Sprinkle each tart with a little demerara sugar.
Bake for 10–12 minutes, until the pastry is completely cooked and the fruit is starting to soften. Leave the tarts in their tins for a couple of minutes, then remove and place a cherry in the middle of each tart (if using). Serve the tarts warm with a spoonful of crème fraiche on top, so it softens in the warmth of the nectarines.