1. Beat the butter, cashew nut butter and sugar in a large bowl, until smooth. Add the egg and vanilla essence and beat well.
  2. Sift in the flour and salt and mix, until just combined. Wrap in plastic film and chill for 1 hour.
  3. Preheat the oven to180C. Line 2 baking trays with baking paper.
  4. Take heaped tablespoons of the mixture, roll into balls and place on the prepared trays.
  5. Dip a fork into some flour and flatten the balls, cresting a criss-cross pattern.
  6. Top with the chopped nuts. Bake for about 12 minutes, until golden.