In a bowl mix sifted flour, icing sugar, salt, butter and egg until becomes dough and knead. Sprinkle some flour to your working area and knead it to form a ball and wrap in a cling film. Refrigerate the dough for about 25 to 30 minutes or until it is workable state.
To make the Caramel filling: Combine all the filling ingredients except pistachio nuts, in a saucepan and bring to simmer until thickens or spreadable consistency. Fire off and set aside to cool completely.
Preheat oven to 180C (350F). When the dough is ready, cut 24 equal portions and flatten each pastry ball on a flour and place each dough on a prepared tart moulds. Press dough in the mould by circular motion, using your thumbs then tidy up the edges with your index fingers. Prick the dough with fork to get rid air pockets and to avoid the dough from shrinking when baking.
Prepare the filling and spread about 2/3’s full on each moulds. Sprinkle each Caramel Tart with chopped pistachio nuts or pipe a meringue icing on top. Arrange caramel tarts on a baking tray and bake in a preheated oven for about 20-25 minutes or until pastry turns light brown and filling gets firm. Remove tarts from the oven and let it cool completely, before removing from the moulds to prevent from cracking.
You can wrap in any colored cellophane if desired, or store in an airtight container.