• Preheat the oven to 170°C (338°F).
• In a food processor or blender, pulse the pistachios into a fine-medium crumb. Set aside a spoonful for garnish.
• In a large bowl, beat the softened butter, powdered sugar, and vanilla together until smooth and creamy.
• Add the all-purpose flour and crushed pistachios to the butter mixture. Stir with a spatula or mix with your hands until the dough comes together and no flour remains visible.
• Shape the dough into a ball, then pat it down into a thick disc.
• Place the dough between two sheets of parchment paper and use a rolling pin to roll it out to a 5mm (¼ inch) thickness.
• Cut the dough into rounds using a 2.5” (6.35 cm) round cookie cutter.
• Place the cookie rounds on a parchment-lined baking sheet and bake in the preheated oven for 12-15 minutes, or until the edges are lightly golden.
• Once baked, transfer the baking sheet to a wire rack and allow the cookies to cool completely.

Garnish

• Break the white chocolate into small pieces and melt it in the microwave in 30-second intervals, stirring between each interval until smooth.
• Drizzle the melted white chocolate over the cooled cookies.
• Sprinkle the cookies with the reserved crushed pistachios before the chocolate sets.