Using a hand mixer, cream the butter and sugar for 2-3 minutes, until well combined. Do not overbeat.
Then, add the egg and vanilla essence and mix until well combined.
In a separate bowl, sift together the flour, baking powder and salt.
Add the flour mixture to the butter mixture, and, using your hands, mix until just combined.
Work the mixture into a dough, and form 2 balls
Wrap the dough in cling wrap, and refrigerate for 1 hour. You can also freeze the dough if you want to use it later.
After one hour, preheat the oven to 180C
Roll out the dough, approximately ¼ inch thick, and using a cookie cutter, or the rim of a glass, cut out even circles.
Place these on you baking tray (lined with baking/parchment paper)
Bake for 10-13 minutes, or until the edges of the cookies are slightly brown.
Cool completely on a cooling rack before eating.
Repeat the process with the 2nd dough ball.