Sweet flan pastry

1. Put the butter, cut into pieces, with the flour, sugar and salt, into a mixer.
2. Work it until the mixture resembles coarse semolina.
3. Add the egg yolk and the whole egg and do not work the machine for a moment longer than necessary (very important) to amalgamate the eggs with the flour mixture.
4. Form it into a ball and leave it to rest in the refrigerator for several hours before using it.
5. (the pastry will keep very well in the refrigerator for a few days, wrapped in transparent film).