Like all liqueurs, this shrub improves with keeping. The finished drink is very evocative of warm Hawaiian evenings, so serve it well chilled with ice.
3 medium-sized pineapples, peeled, cored and chopped
4 pints rum
9 oz. sugar
Put the chopped pineapples into an electric blender, a little at a time. Blend at high speed until the pineapples are completely crushed.
In a large mixing bowl, combine the blended pineapples, rum and sugar together, stirring until the sugar dissolves.
Strain the shrub through a layer of fine cheesecloth into clean, dry bottles. Seal the bottles and set them aside for at least 2 months before serving.