Fill a highball glass to the top with crushed ice
Place 3 bar spoons of bilberries into a shaker and muddle
Pour in 0.35 oz of lime juice, 0.35 oz of creme de cassis liqueur, 0.35 oz of blueberry liqueur and 1 oz of white rum
Fill the shaker with ice cubes and shake
Finely strain into the highball glass
Top up with Sprite and stir gently
Top up with crushed ice
Garnish with a rosemary sprig