1 teaspoon Instant Coffee (Dissolved in boiling water.)
Line a 20cm square tin with silicone baking paper
Place the sugar, golden syrup and cream in a large saucepan and heat gently till the sugar dissolves.
Bring the mixture to a rapid boil. If you have a sugar thermometer (I don't), boil until the mixture reaches 116c/240f) After 5-10 minutes you should see the mixture start to subside. At this stage add in the coffee and test by dropping a small amount into a cup of cold water. If it forms a soft ball it is ready. Stir through the walnuts.
Remove from the heat and beat until the mixture becomes thick, grainy and matt. This will take 5 - 10 minutes and in my experience it's worth setting your kitchen timer so you can keep a check on how long you have been beating for!
Pour into the tin and leave for 30 minutes before marking out squares with a round ended knife.
Leave until cool and set. Cut into pieces and store in an airtight tin, lined with more baking paper.