200g plain flour 2 tbsp icing sugar 100g unsalted butter, chilled and cubed 2 large egg yolks, beaten
1 tbsp icing sugar, sifted
First, make the pastry. Sift the flour, a pinch of salt and icing sugar into a large mixing bowl. Using your fingertips, rub the butter into the flour until the mixture resembles fine breadcrumbs and there are no large lumps of butter left. You can also place the ingredients in a food processor and pulse until you get the same effect.
Stir in half the beaten egg yolks until the mixture comes together. If the pastry won't come together, it is too crumbly or too wet. In the former case, add a few tbsp of water; in the latter, add a little more flour. Continue to add the remaining egg yolk, adding just enough until it binds into a soft but not sticky dough. You can add some water if your pastry is very dry, to make it easier to handle. However, if you can manage a fairly dry pastry, the end result will be more pleasingly crumbly. Push the pastry together and shape into a flat circle. Wrap in clingfilm and chill for half an hour in the fridge.
Unwrap the pastry and transfer to a lightly floured work surface. Lightly flour a rolling pin and roll the pastry out until it is 3mm thick – about the thickness of a pound coin. Pick up the pastry with the rolling pin and use to line the tart tin. Trim the edges with a knife. Press well into the corners, using a ball of spare pastry to gently stretch it into place. Chill for another half an hour in the fridge.
Preheat the oven to 190°C, gas mark 5. Lightly prick the pastry with a fork to stop it rising. Line with baking parchment and fill with baking beans to help it keep its shape and stop the sides collapsing. Place on a baking sheet to make it easier to slip in and out of the oven and bake for 15 minutes. Remove the baking beans and parchment and return to the oven for 5 minutes until lightly golden and dry to the touch. Allow to cool, then spread jam over the pastry. Turn the oven down to 180°C, gas mark 4.
To make the filling, place the butter and sugar in a bowl and beat together until pale and fluffy. Begin adding the eggs, a little at a time – they could curdle if you add them too fast. (Having everything at the same temperature helps avoid this outcome, too.) Add the almond extract and fold in the ground almonds. Spoon the mixture over the jam and level it out with the back of a spoon. Sprinkle over the flaked almonds. Return the tart to the baking sheet and place on the middle shelf of the oven for 30–35 minutes, or until the filling is golden on top and feels firm in the middle. If the tart seems to be browning too quickly, cover with a sheet of foil. If your oven is uneven, turn once during cooking.
Remove from the oven, allow to cool slightly, and then remove from the tin and dust with icing sugar. Slice into 8 portions and serve.