2) Sift the wholemeal flour, cornflour, ginger, salt and bicarbonate of soda together in a medium bowl. Stir in the oat/nut mixture.
3) In another medium bowl, beat the butter with an electric mixer for about 1 minute until smooth and light. Gradually add the caster and light brown sugar and continue beating for about 3 minutes more, until everything is evenly combined.
4) Add the vanilla and the egg then mix in the dry ingredients to make a textured dough.
5) Line a 1.5L loaf pan (or 3 mini loaf pans) with cling film, pack dough into the bottom half of the pan and press to level off. Cover with cling film and refrigerate for about 2 hours until completely firm.
6) Preheat the oven to 180C/Gas 4. Line 2 baking sheets with parchment paper or silicone mats.
7) Remove dough from the pan, unwrap and slice in half lengthwise if using a large pan. Slice each half crosswise into 0.5cm thick cookies. Place the cookies about a 2.5cm apart on the prepared pans.
8) Bake for 15 to 18 minutes, until golden brown. Transfer cookies to a rack to cool down and crisp up.
May be stored in a tightly sealed container for up to 1 week.