In a separate bowl sift the flour with salt. Set aside.
Cream butter,add sugar and beat until its smooth - it takes about 5mins. Add vanilla essence and mix well.
Now add APF to the butter sugar mixture and bring it to a dough. Flatten the dough into disk shape, wrap in a plastic cover and refrigerate for an hr.
On a flat surface roll out the dough to 1/4 inch thick. Cut into your desired shapes and place these cookies on the prepared baking sheet and again refrigerate it for 10-15 minutes.This will firm up the dough for the cookies to maintain their shape.
Meanwhile u can preheat the oven to 175deg C for 10mins. Bake the cookies for 12-15 mins.
If you feel like bread crumble texture after mixing the flour, sugar and butter, you can sprinkle few drops of milk to form the dough like texture for easy rolling and cutting.
This makes 20 shortbreads. This kept in an airtight container will go well for a week.