Preheat the oven to 160 C / Gas 2 1/2. Grease a tart tin.
Sift the flour, cornflour and sugar into a large bowl. If you choose to add the vanilla pod, slice it down the middle and scoop out the seeds with a knife, then add to the flour mix. Add the butter and rub into the mixture until the ingredients bind together.
Put the dough into greased tart tin and press down evenly over the base. To make sure it doesn't crumble when you take it out of the tin, make sure you press the mixture down really hard. Prick the surface with a fork and sprinkle on the chocolate chips and press them lightly into the surface.
Bake the shortcake in the preheated oven for 35 to 45 minutes. Mark out 8 slices with a sharp knife and cool for 10 minutes, then transfer to wire rack to cool completely.