Preheat oven to 350F. Lightly grease 2 baking sheets, or use parchment paper.

Put the butter and sugar in a mixing bowl and cream together. Add the flour and vanilla to the creamed mixture and mix until thoroughly combined.

Spoon the mixture into a large piping bag fitted with a large star nozzle and pipe 4-5 inch lines onto the prepared baking sheets, leaving space for expansion. (I made mine about 3 inches).

Cook for 15-20 minutes, until pale golden brown. Leave on the baking sheets to cool slightly before lifting on to a wire rack. Leave the cookies to cool completely.

Put the chocolate in a small heatproof bowl and melt over a pan of hot, but not boiling water. Dip both ends of each cookie into the melted chocolate, return the cookies to the wire rack or set on parchment paper to set.