Begin by making the pastry as described in shortcrust pastry.
Then leave it to rest in a polythene bag in the refrigerator for 30 minutes before you roll it out as described in the shortcrust pastry recipe to 28cm in diameter then carefully roll the pastry round the rolling pin and transfer it to the centre of the tin.
Now, using your hands, gently press the pastry into the tin to line the base and sides making sure you ease the pastry into the corners and press it against the sides then trim off any excess pastry around the top edge with a sharp knife.
After that use your fingers again to press the sides all round to the pastry so it is slightly proud of the tin.
All you now need to do is prick the base all over with a fork, as this will release any trapped air, which is what causes the centre to rise up.
Then pop it in the freezer to chill for 30 minutes.
Pre-heat the oven to 190°C gas mark 5 with the baking sheet on the shelf nearest the centre.
Once the pastry case is frozen put it on a flat surface. Place the piece of foil over it, then press it down over the base and up the sides of the pastry then turn the edge of foil inwards and crumple it against the sides to create a support that will hold the pastry in place whilst it cooks.
Put the pastry case onto the pre-heated tray in the oven and bake for 15 minutes. Then remove the pastry case from the oven and ease the sides of the foil inwards and carefully lift it away from the pastry case (you can reserve this foil liner to use another time).
Brush the base and sides all over with beaten egg (use a little from the filling), which will provide a sort of waterproof coating so that the pastry stays beautifully crisp even after the filling has gone in.
Now return the pastry case to the oven for 8 minutes.
Remove the cooked pastry case from the oven and reduce the oven temperature to 180°C, gas mark 4.
Now place the cream and butter in a saucepan and bring it up to a gentle simmer, then whisk the beaten eggs and sugar together in a large heatproof jug using a balloon whisk – but not too vigorously because you don't want to make bubbles.
Then pour the hot liquid over the beaten eggs, add the vanilla extract and half the freshly grated nutmeg and whisk briefly again.
Pour the filling into the tart case and grate the rest of the nutmeg all over. (If your prefer you can pour the filling directly from the jug.
Place the pastry case on the baking sheet in the oven, and then pour the filling straight into the pastry, which avoids having to carry the tart to the oven and spilling it).
Then bake in the oven for 40 minutes, until the filling is just set in the centre.
Serve with clotted cream, either warm or, as I actually prefer it, cold.