Milkshakes have always seemed to me the height of decadence: a dessert cunningly masquerading as a refreshing drink, and that’s even without the ice-cream that most of the world seems to regard as an essential ingredient. Strawberries, with their famous affinity with all things creamy, are the perfect summery subject–sweet enough to please, sharp enough not to be cloying, and perhaps the ultimate treat when it’s too hot to cook.