Preheat oven to 170C/325F/gas 3.
Grease the tart tin with butter.
To make the pastry sift the flour and salt into a large mixing bowl.
Cut the butter into very small chunks, add them to the bowl and stir them in.
Add the cold water and bring together to a wet dough with a lumpy consistency.
Cover with clingfilm and place in the fridge for 30 minutes.
Place the dough on a floured work surface and shape into a rectangular block.
Roll the dough to a rectangle three times longer than it is short, keeping the edges straight and even. The rolled-out pastry should have a marbled effect from the lumps of butter.
Fold the top third down to the centre, then the bottom third up and over that.
Repeat the folding and rolling out twice more.
Fold one last time, cover with clingfilm and place in the fridge for 30 minutes.
Give it a quarter turn and roll out again to the original sized rectangle.
Repeat the folding, turning and rolling out 3 more times or until the marbling effect has disappeared. Fold once more and place in the fridge for 30 minutes.
Remove the dough from the fridge and place on a lightly floured work surface.
Roll out to 2mm thick and line the tart tin.
Prick the bottom of the pastry case with a fork and place in the fridge for 30 minutes.
To make the filling place the butter and sugar in a large mixing bowl and beat with the electric hand whisk until light and fluffy.
Add the egg yolks and eggs one at a time, beating in well after each addition.
Add the cream and whisk in.
Take the pastry case out of the fridge and pour the filling mixture into it.
Place in the oven and bake for 45 minutes until the custard is set and golden. Check after 25 minutes or so that the top of the tart isn’t burning. If it is place, a piece of kitchen foil over the top.
Remove from the oven and allow to cool to room temperature before removing the tart tin and transferring to a serving plate.
