Of course, I couldn't just cook them entirely sour. I'm not that much of a glutton for punishment. To the berries I added two teaspoons of sugar, one teaspoon of finely grated orange zest, and the juice of one orange. That's how easy it is. Then I just left it to simmer over a slow heat for a while; this took maybe twenty minutes at the most. I don't really know, because I was somewhat distracted by the careful unveiling of the cake. ;)
Oh, and while I remember, you should all learn from my mistakes: make sure that you puncture the berries with a knife so that they don't explode. The first explosion sent a small amount of delicious cranberry in a decorative streak across the stovetop. I quickly removed the berries from the heat, cleaned up the offender, and popped the rest with a small paring knife, so as to avoid further waste. I hate wasting food, but I hate it even more when it's this delicious.
Of course, you could just circumnavigate that process completely by cutting the cranberries in half before you cook them. Previously, I'd never know that cranberries are white in the centre. I'd simply bought them frozen and used them whole in a cranberry teacake, or used the dried ones in muesli and biscuits. So it was nice to play with fresh ones, and perhaps I'll do that again one day; whenever I'm next in the USA, maybe! Oh, dreams of travel...
Speaking of dreams, this cake freezes really well. I know that individually wrapping it isn't a good idea because of the environmental complications, but I do use this method occasionally, when I have limited freezer space. The girlfriend of my housemate has moved in for 6 weeks (much longer than I was warned about!) before they move into their own apartment, so I'll just have to accept being an environmental vandal until then. I'm thankful that I'm going travelling with my sister over Christmas, I'll say that much. So, if you're like me and you've frozen half of your cake to take as morning tea to your study or work commitments, then use the rest of this compote over fresh bread, or even mixed into some warm oats. You won't regret it.