This is so ridiculously simple that I am reluctant to deem it a recipe, to be honest!
Serve hot with ice cream, or chill and put on top of a cheesecake (which is what I did).
1 packet of blueberries
2 dessertspoons of caster sugar
Put blueberries and sugar in a heavy based pan, and warm over medium heat until the sugar has melted and the blueberries are glossy.