Add vanilla, beat till just combined. Fold in flour and salt in two portions.
When the dough has formed, wrap in plastic wrap and refrigerate for 30 minutes.
On a lightly floured surface or pastry cloth, roll dough out to 1/4" thickness and work quickly with a floured cookie cutter.
Bake on parchment paper at 175C(350F) for about 12 mins or till cookies start to brown around the edges. Allow to cool before removing from parchment. Watch them carefully as they brown very quickly once they start around the edges.
Melt the bakers' chocolate (I used 56% coverture) and dip part of the cookies in the chocolate and place back on parchment to set.