I took a basic muffin recipe and added a couple of things to make it something a little special. The sharpness of the raspberries contrasts brilliantly with the sweetness of the white chocolate. It's pretty foolproof too, which is a big bonus
You can use regular caster sugar, but I use golden caster sugar which has a nicer flavour.
Frozen raspberries work brilliantly, I don't even bother to defrost them.