Line the baking tray with parchment paper.

Assemble the Food Processor bowl onto the power unit.

Fit the Knife Blade to the Food Processor bowl.

Add Ingredients 1 (flour, sugar, pistachios) into the Food Processor bowl.

Attach the lid and ensure it is locked into place.

Mix on a high speed until pistachios are finely chopped.

Add the first item of Ingredients 2 (butter) to the bowl.

Pulse until the mixture resembles fine breadcrumbs.

Add the remaining item of Ingredients 2 (yolks) to the bowl.

Pulse until the mixture comes together.

Transfer dough to a lightly floured worksurface.

Briefly knead the dough and gently shape into a ball.

Wrap with parchment paper.

Chill in the fridge for 1 hour.

Remove the dough from the fridge and let rest for 20 minutes.

Preheat an oven to 160°C.

Roll the dough out to approx. 0.5 cm thick.

Cut circles out of the dough using a 6 cm round cutter.

Transfer dough circles to the lined baking tray.

Bake for 15 minutes at 160°C until golden brown.

Let cool.

Retrieve, clean the Food Processor bowl and fit the Whisk Tool.

Add Ingredients 3 (egg whites) into the Food Processor bowl.

Whisk on a medium speed for 2 minutes until foamy.

Remove the Whisk Tool from the machine and fit the Knife Blade.

With the machine running, gradually add Ingredients 4 (sugar, lemon juice) into the Food Processor bowl.

Mix on a medium speed for 30 seconds until thickened.

Spread icing over the cooled shortbread biscuits.

Top each shortbread biscuit with Ingredients 5 (viola).

Press down gently and leave to dry.

Serve.