Dissolve the sugar, butter, cream and liquid glucose together in a large saucepan, stir frequently to prevent catching.
Bring to the boil, do not stir, and simmer until the syrup reaches 245°C – to ‘soft ball stage’.
You can test this by dropping some of the syrup into cold water – if it forms a soft ball, it’s the perfect temperature.
Remove from the heat and allow the syrup to cool to 215°C.
Move the mixture into the bowl of a fixed head beater and whisk on slow speed for 1 minute, increasing the speed as you go.
Beat vigorously for five minutes, or until the mixture can just hold its shape.
Add the icing sugar, then Old Pulteney whisky, and continue to stir at low speed for another 30 seconds.
Turn into a tin and allow to cool for a couple of hours or until firm enough to cut into squares.