Fill a rocks glass to the top with crushed ice
Pour in 0.5 oz of lime juice, 1.5 oz of grapefruit juice, 0.5 oz of sugar syrup, 1 oz of Campari and 1 oz of Highland single-malt whiskey
Add 3 dashes of homemade milano bitters
Give it a good swizzle
Top up with crushed ice
Garnish with lemon zest and a mint sprig