1 lemongrass, roughly chopped
1 piece pared lime zest
1 large pineapple, peeled and cut into thick slices
200g/7oz demerara sugar
few star anise, broken up
50²µ/1ΒΎ΄Η³ϊ butter
crème fraîche, ice cream or coconut-flavoured dairy-free ice cream
100ml/3Β½fl oz rum