I first tried these from Sainsburys a few years ago - courtesy of my sister in law. They are very rich but full of flavour. Needless to say because I liked them (and they were expensive) I decided to search for a recipe to have a go myself and here it is.
For the pastry:
6oz plain flour
3 oz unsalted butter
1 large egg beaten
For the filling:
2oz unsalted butter
8 oz sultanas
2 large eggs
2oz demerara sugar
2 teaspoons white wine vinegar
Preheat your oven to 350 degrees F/180 degrees C or Gas Mark 4
You can either make a tart or individual tartlets the choice is yours
First make the pastry gently rubbing in the flour and butter until like very fine breadcrumbs. Add the egg mixing in to make a stiff dough.
Roll out the pastry then line the flan dish/or cut out individual tart basis to fill a patty tin.
For the filling
Melt the butter in a pan and add the remaining ingredients. Stir well then add the mixture to the pastry case/cases. Bake for approximately 35 minutes until golden brown and set.