Make the crust:
You can do this by hand or in the food processor. I find the food processor excellent for making pie/ tart dough.
Sift the flour into a bowl. Add the butter and rub with fingertips into the flour, till the mixture resembles coarse bread crumbs.
Add 2 tbsp water and using your hands, bring the dough together adding a little water if necessary. Too much water will result in a tough pastry.
Turn the dough onto a lightly floured work surface and knead briefly till dough is smooth.
Form into a neat ball, flatten into a round, wrap in cling film and chill for at least 30 minutes.
Remove pastry from the fridge and place on lightly floured surface and roll out into a circle about 12u201d in diameter, slightly larger than a 9u201d fluted pastry ring/ dish. Roll the pastry in a back and forth motion and do not stretch or pull the pastry.
Place the pastry circle in the ring/ dish and carefully press to the edges, removing excess pastry with a knife. Lightly prick the base with a fork. Chill for about 20 minutes.
Remove from the fridge and line the pastry with foil or waxed paper, and fill with baking beans.
Bake at 200C for 12 minutes. Remove the foil/ waxed paper and put the crust back in the oven for another 10 minutes till golden brown.
Cool on a wire rack.
Make the filling:
Pour the grape juice (one litre) into a pan and bring to a boil. Then turn down the heat to low-medium and simmer, while stirring frequently, till it has reduced to 150 ml. Once the juice has reduced to roughly 1/3rd, watch the pan and its contents or you will end up with a burnt liquid! Let this cool to room temperature.
Put the milk, cream, cornstarch and flour into a pan. Mix well, and cook the mixture over medium heat till it becomes a smooth and thick paste. Add the butter and mix well. Let this cool.
In a small bowl, whisk the egg, sugar and vanilla extract. Add to the cooked and cooled mixture. Mix well. Now add the reduced grape juice and mix well. You might find your tart filling seems a little granular but thatu2019s fine.
Assembling the tart:
Pour the filling into the tart shell and bake at 200C for about 40 minutes. The filling will have set well. Do not be tempted to cook for longer or the texture of the filling will change.
Cool the tart well before slicing.