Heat the cream, glucose, fennel seeds and salt in a small heavy-based saucepan over medium heat to simmering point, then remove from the heat. Leave for 20 minutes to infuse. Strain through a fine-mesh sieve into a heatproof bowl.
In another saucepan, heat the caster sugar and water over high heat, without stirring, for 6–8 minutes or until the sugar syrup turns a