Mix the butter in the bowl of your food processor using the leaf until it becomes soft
Then add in order: the sifted icing sugar, the salt, Vanilla, the egg, then the sifted flour.
Knead until the dough forms a ball, then do not insist too much because the dough may shrink and be more brittle when cooked.
Let it rest for half an hour in the fridge in a plastic wrap
Then preheat the convection oven to 170 °, line the dough with baking paper and fill with dry beans to prevent the dough from swelling.
Bake 20 minutes then remove the paper and put the pie shell back to bake for about 10 minutes. Leave to cool on a rack.