Get the butter out of the refrigerator at least an hour before baking. It should be soft to the touch, but not melted.
Cream the butter, sugar and vanilla extract with a handheld or stand mixer for 5 to 8 minutes. The creamed butter and sugar should be light in color and fluffy in texture. SEE NOTE 2
Use a spatula to scrape the dough of the side of the bowl. Sift the flour, 1/3 cup ( 40g at a time folding it gently into the creamed butter mixture, until you have used up all the flour.
Transfer the dough to a sheet of plastic wrap and roll it to form a log. Cut a hole in one end of the plastic wrap and place it into a piping bag fitted with a flower tipped nozzle. SEE NOTE 3
Pipe the dough using a 1M open star piping tip onto a baking sheet lined with parchment/baking paper. If you feeling that the dough is too stiff or hard to pipe, then just add a tablespoon of warm milk to the dough. This will make the dough softer and easier for you to pipe.) SEE NOTE 4
Place the baking sheet into the refrigerator for 30 minutes to firm up the piped cookies. This prevents the dough from spreading while baking ensuring that the cookies keep their beautiful piped shape.
Sprinkle granulated sugar over the cookies before baking if preferred or leave plain.
Bake in a preheated oven of 300°F/ 150°C (148°C fan)for 15 minutes or until the edges begin to turn a golden color.
Remove from the oven and leave the cookies on the baking sheet to cool for 10 minutes before serving or store in an airtight container.