Method

• 1.
  To clarify butter, place butter in a small pan over low heat for 4-6 minutes, allowing it to melt gently. Remove from heat and pour into a small heatproof jug. Set aside for 1-2 minutes until it separates into two layers – a milky, white layer on the bottom and the liquid (clarified) butter on top. Discard any skin that might have formed, then measure out 1/2 cup (125ml) clarified butter. Discard the milk solids.
• 2.
  Meanwhile, combine the flour, baking powder, 1/4 tsp salt and cardamom in a bowl, and stir with a whisk to aerate.
• 3.
  Place icing sugar in a bowl and whisk in the clarified butter, whisking well for 1-2 minutes until smooth. Stir in the vanilla and rosewater, then stir in flour mixture. Bring the mixture together with your hands until a smooth dough forms – it should be a bit sandy and should just hold together if you squeeze a little in your palm.
• 4.
  Lay a large piece of baking paper, with a long side nearest to you, on the bench. Tip the dough along the length of the paper and bring it together as best you can to form a log about 4cm x 18cm. Roll the log up in paper and twist the ends tightly in opposite directions to seal. Chill the log for an hour or so until it’s fairly firm.
• 5.
  Preheat the oven to 150°C and line 1-2 baking trays with baking paper.
• 6.
  Unwrap the log and cut it into 24 rounds (about 5mm thick), using a gentle rocking motion with the knife as the mixture is a bit crumbly. (If the slices break up as you cut them, the dough is too cold. Leave at room temperature to warm up, then try again.)
• 7.
  Sit biscuits on prepared trays, leaving a 2cm gap between each. Gently press some pistachios onto each biscuit and bake for 20-25 minutes until they look just a shade or two darker all over. Halfway through the cooking time, turn tray around so biscuits cook evenly. Leave them to firm up on the tray for a few minutes, then carefully transfer to a wire rack to cool completely. Store in an airtight container in a cool spot for up to 1 week.