Preheat the oven to 190'C.
Melt the butter in a heatproof bowl over simmering water (bain marie).
In a separate bowl mix together the flour, ginger, bicarbonate of soda and salt. In another bowl, combine the melted butter, sugar, brown sugar and vanilla extract until creamy. Beat in the eggs. Gradually beat in the flour mixture and then add the chocolate chips.
Shape the dough into a sausage shape, wrap in cling film and chill until firm.
Cut the dough into discs and place them on a baking sheet lined with a silicone baking mat or parchment paper. Leave a space between the discs as the biscuits will spread as they cook.
Bake in the oven for 10 to 12 minutes. Remove from the oven when golden.
«The biscuits will become firm and crunchy as they cool. Remove them carefully from the baking tray whilst warm and then allow them to cool on a wire rack.»