Heat all ingredients in a saucepan until the sugar has dissolved, then chill completely. Churn in an ice-cream machine to manufacturers instructions.
Combine the sugar, glucose, honey, chilli and 1 tbsp water in a saucepan over low heat and stir until the sugar dissolves, then bring to the boil.
Brush down the sides of the pan with a clean wet pastry brush and cook until it turns a light caramel colour (5-7 minutes). Add the bicarbonate of soda and stir quickly with a wooden spoon – it will bubble up vigorously. Quickly pour on to a heatproof tray lined with baking paper and cool completely (15- 20 minutes).
Dust the pineapple very lightly with icing sugar, then grill over medium heat, add the rum – the sugar will caramelise.
To serve, lay the pineapple on a plate, crumble some honeycomb over and top with a quenelle of coconut sorbet.