Preheat the oven to 200C/400F
Making the pastry
Place the flour and salt into a bowl and rub in the butter with your fingers until the mixture looks like fine breadcrumbs. Add the sugar, then add the water and mix gently to make a soft dough. (Or you can make it in a food processor, like this.) Let rest in fridge for 20 minutes or so.
Roll out the dough on a lightly floured surface. Cut into circles to fit your mini tins. Using a fork, press the tines into the bottom and sides of the pastry in the tin, then bake for about 15 to 20 minutes, until partially cooked. Remove and set aside.
Spread the jam on the bottom of the crust then make the frangipane filling.
Making the filling and baking
Melt the butter in a pot, remove from heat and stir in the sugar, ground almonds, egg and almond extract (if using.) Pour the mixture over the jam, but don't fill too full.
Reduce the oven temperature to 350°F(180°C) and bake for about 20 minutes, until golden-brown and a skewer pushed into the middle comes out clean. Remove from the oven and leave to cool completely in the pan.
Make the icing so that it's rather thick, but still runny, and cover each tartlet with the icing.
Immediately draw a design of zig zag lines on the center of the tart, then drag a toothpick or knife thought the design. Allow to set completely before serving or storing.
