Cream Salted Butter (100 gram) and Powdered Confectioners Sugar (125 gram) until pale and combined.
Separate the Egg (1) yolk from the white.
Then, sift in all the dry ingredients, All-Purpose Flour (95 gram), Corn Starch (30 gram), Unsweetened Cocoa Powder (40 gram), and Baking Powder (1/4 cup).
Slowly stir until it forms a dough, then divide the dough into two and chill for at least 30 minutes.
Roll out the dough to about 0.5-cm (1/4-inch) thickness between two sheets of parchment paper to prevent sticking.
Cut out using a 5-cm (2-inches) cookie cutter. Make sure that the cookie cutter is always dusted with flour.
If the dough is too soft to handle at this point, put it in the freezer as it is for 15 minutes before moving the cut-out dough onto a baking tray. Re-roll and repeat the process..
Meanwhile preheat your oven to 360 degrees F (180 degrees C).
Bake the cookies for about 10 minutes at a preheated oven.
Allow the cookie to cool completely before removing it.
To make your pistachio filling, cream together Pistachio Spread (50 gram), Butter (20 gram) until well combined.
Then, beat in sifted Powdered Confectioners Sugar (40 gram).
Pipe out your pistachio filling onto a cookie and sandwich with another. Serve and enjoy!