To toast the sesame seeds, put them in a non-stick pan over medium-low heat and stir every 30 seconds for 4 minutes. Tip these onto a large plate to cool.
Pre-heat oven: 195°C / 175°C (fan) / Gas Mark 5 ½ / 385°F
Cream together the butter, sugar and tahini until you get a smooth mixture.
Sieve in the flours, mixing until a dough starts to form.
Mix in the toasted sesame seeds until spread evenly throughout.
Briefly knead the dough together with your hands until your dough is smooth. Refrigerate for 15mins if it seems sticky.
Spread a little flour onto a clean work surface and your rolling pin, then roll out the dough until roughly ½ cm (¼ inch) thick.
Using a 3cm cookie cutter cut out as many biscuits as you can, re-rolling the trimmings and cutting again as necessary.
Place the biscuits on a baking sheet and poke 3-4 sets of holes using a fork into each biscuit, before baking for 8-10mins until lightly golden.
Allow the biscuits to cool on the tray for 10mins before transferring to a cooling rack, as they will be fragile when first leaving the oven.
Matcha chocolate dip:
Once the shortbread has cooled (roughly 15mins after baking), make the matcha chocolate dip. In a microwave (20 secs at a time) or over a double boiler, slowly melt the white chocolate in a bowl, stirring until smooth.
Sieve in the matcha powder and stir until smooth.
Dip one side of each shortbread into the liquid matcha chocolate, allowing the excess to drip off into the bowl before placing them on greaseproof paper on a flat surface.
Place the dipped biscuits into the fridge for the chocolate to set for 15mins.