Heavily adapted from a gluten-free ginger biscuit recipe. I also had to add half an egg, as I was having trouble getting the dough to come together properly.
You can cut down on the amount of crystallized ginger if you want.

100g/4oz unsalted butter, softened
50g/2oz caster sugar
175g/6oz plain flour
½ teaspoon baking powder
1 teaspoon ground ginger
50g/2oz crystallized stem ginger, finely chopped
½ a beaten egg

100g/4oz white chocolate, melted
100g/4oz dark or milk chocolate, melted

In a large mixing bowl, beat the butter and sugar together until light and creamy. Add the plain flour, baking powder, ground ginger and the finely chopped crystallized ginger. Stir to form a stiff dough, adding the beaten egg gradually.

Roll out the dough onto a lighly floured surface to about 3mm thick and cut out with a cookie cutter. Place the shapes onto baking sheets and place in the fridge for half an hour or so. You can re-roll the the trimmings to make more biscuits.

Pre-heat the oven to 180ºC/360ºF and bake the biscuits for about 15 minutes, until pale, golden and just crisp. Transfer onto a wire rack to cool and dip into the chocolate, or drizzzle melted chocolate on top. Leave to set.