In a large mixing bowl, cream together softened butter and powdered sugar until smooth and fluffy (2–3 minutes). Stir in the vanilla extract and orange zest if using.

Gradually mix in the flour and salt until fully incorporated. The dough will be soft and crumbly. Stir in the cranberries and pistachios until evenly distributed.

Divide the dough in half. Roll each half into a log about 2 inches in diameter. Wrap in plastic wrap and chill in the fridge for at least 1 hour or freeze for up to 3 months.

Preheat oven to 325°F (160°C) and line a baking sheet with parchment paper.

Remove dough from the fridge and slice into ¼-inch thick rounds. Place on prepared baking sheet, spacing slightly apart.

Bake for 14–16 minutes, or until the edges just begin to turn golden. Do not overbake — they should remain pale and tender.

Let cool on the baking sheet for 5 minutes, then transfer to a wire rack.

Store in an airtight container at room temperature for up to 1 week.