Preheat the oven to 180'C.
Cut the butter into small cubes. Place the butter into the bowl of a food processor with the flour, salt, green tea powder and caster sugar. Fit the paddle to your food processor and slowly combine the ingredients until you have a ball. Place the ball between 2 sheets of parchment and roll it to a thickness of 5mm. Place the rolled dough into the fridge and refrigerate for 30 minutes. Remove from the fridge and use a pastry cutter to cut small biscuits. Bake in the oven on a baking sheet for 10-12 minutes until golden brown.
When cooked, allow the biscuits to cool on a rack.
Cut the chocolate into small pieces if necessary.
Place 300 grams of the chocolate into a heatproof bowl and melt it over a saucepan of simmering water. Stir the chocolate to ensure it is melting evenly. Check the temperature of the melting chocolate with a thermometer and allow it to reach a temperature of 45'C.
When the chocolate reaches 45'C remove the bowl from the heat and stir in the remaining 150 grams of chocolate. By adding the un-melted chocolate the temperature of the melted chocolate will naturally decrease. In order to temper the chocolate the temperature of the chocolate needs to reach 31'C. If it goes lower than 31'C, place the bowl back over the simmering water and bring the chocolate up to the correct temperature.
To finish the biscuits dip them into the chocolate and then place the dipped biscuits onto a rack to allow any excess to drain off. Allow the chocolate to cool completely before serving your biscuits.
«Vary the flavour of the biscuits by replacing the green tea with powdered spices such as cinnamon, five spices or gingerbread mix.»