Tourte limousine, a covered potato pie with herbs and cream

Pulse the flour, salt and sugar together in a food processor.

Add the diced chilled butter and pulse until the flour is coated and it looks like grains of sand, then add the chilled shortening and pulse a couple of times.

Stream in the very cold water with the machine running until it forms small lumps that hold their shape when squeezed in the palm.

Gather into a rough mass and smear it a couple of times with the heel of the hand for a final blending.

Wrap in plastic and chill two hours.

Peel the potatoes and slice them thinly on a mandolin, holding them in water.

Pick chives, parsley and basil; rinse, rough chop the parsley and mince the chives, leaving the basil until last so it does not oxidize.

Butter the inside of the nine-inch springform pan and lightly flour the work surface.

Roll the pastry into a 14 inch circle and line the springform with about an inch and a half of overhang, patching where needed.

Cut the basil in chiffonade and mince it. Preheat the oven to 425F.

Melt four tablespoons of butter and stir in the parsley, basil and chives.

Drain and dry the potatoes. Layer a third into the lined pastry, pour over a third of the herb butter, salt and crack pepper, and repeat twice more.

Fold the overhanging pastry over the potatoes, patch any holes, and brush the top of that pastry with water.

Roll the remaining dough into a nine and a half inch circle, lay it on and press it down over the moistened pastry underneath.

Cut a chimney hole in the centre of the lid and fit a piping bag nozzle into it.

Brush beaten egg over the top and make crosshatch marks with the tines of a table fork, in both directions.

Bake in the lower part of the oven at 425F for 30 minutes until nicely but not too deeply brown.

Mix one third cup of heavy cream with the remaining egg and refrigerate until needed.

Turn the oven down to 350F and bake a further 30 minutes, one hour in total.

Remove the chimney, check the potatoes are tender with a thermometer through the hole, then pour the egg cream mixture in by spoonfuls, tilting in all directions. It did not disperse past the centre and he stopped early.

Bake a further five minutes so the cream and egg mixture sets.

Release the springform, set on a board and place a little parsley in the centre before cutting.