Preheat oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine butter, brown sugar, granulated sugar, flour, salt, vanilla, and a little milk to form a cookie dough.
Stir in the chocolate chips until well distributed.
Roll out the puff pastry and spread the cookie dough mixture over half of it.
Fold the other half of the pastry over the cookie dough and gently press down.
Cut into strips and twist each strip carefully.
Place on the baking sheet and bake for 12-15 minutes or until golden brown.
Let cool slightly, then dust with powdered sugar if desired.