Bash the rosemary a few times with the back of a knife and pop it into a heat-proof bowl.

Heat the syrup to a simmer and pour over the rosemary. Let steep until room temperature. Pass through a fine sieve and store in the fridge. The syrup will keep for up to a week.

Combine 25ml of the rosemary syrup in a tall glass with the lemon juice, tonic and 50ml of Captain Morgan Sliced Apple.

Garnish with a slice of apple and a fresh rosemary sprig.