With a creamy chocolate centre and pastry that melts in your mouth, this tart is delicious accompanied by a whisky-flavoured ice cream or a spoonful of vanilla-flavoured crème fraîche.
To make the pastry, cream the butter and sugar together with a wooden spoon. Gradually beat in the combined egg and vanilla, beating well after each addition. (The mixture may look slightly curdled.) Add the flour and salt, and mix lightly until smooth. Do not overmix. Gather the pastry together into a rough ball. Flatten with the palm of your hand to a thickness of