Step 1: 1) Preheat oven to 140 degrees C. Line two baking sheets with parchment paper and have a pastry bag with a plain tip (about 1/2-inch, 2 cm) ready.

Step 2: Grind together the powdered sugar with the almond powder and cocoa so there are no lumps; use a blender or food processor since almond meal that you buy isn't quite fine enough.

Step 3: In the bowl of a standing electric mixer, beat the egg whites until they begin to rise and hold their shape. While whipping, beat in the granulated sugar until very stiff and firm, about 2 minutes.

Step 4: Carefully fold the dry ingredients, in two batches, into the beaten egg whites with a flexible rubber spatula. When the mixture is just smooth and there are no streaks of egg white, stop folding and scrape the batter into the pastry bag.

Step 5: Pipe the batter on the parchment-lined baking sheets in 1-inch (3 cm) circles (about 1 tablespoon each of batter), evenly spaced one-inch (3 cm) apart. Rap the baking sheet a few times firmly on the counter top to flatten the macarons, then bake them for 15-18 minutes.

Step 6: 2) Run the pistachio, sugar and colour in a nut/coffee grinder till well ground. Whisk the butter till smooth for a minute, add the nut mix & blend.

Step 7: Pipe onto cookies & sandwich.