For me, the real test of a great chocolate brownie is that it's so gooey and rich in chocolate that you're only just able to pick it up. I've added some dried cranberries here, but there is no reason you shouldn't use cherries instead if you prefer.
250g unsalted butter, melted
70g cocoa powder
110g good-quality dark chocolate, melted in a bain-marie or microwave
5 eggs, beaten
500g caster sugar
140g plain flour
110g walnuts, chopped
100g sun-dried cranberries
1tsp baking powder
Preheat the oven to 175C/gas mark 4. Mix the butter, cocoa powder and melted chocolate together. In a mixing machine, or by hand, whisk the eggs and caster sugar until they are light and fluffy. Mix this with the melted chocolate and butter, chopped walnuts and cranberries.
Next sieve the flour and baking powder together and carefully fold it into the mixture. Line a deep baking tray with buttered greaseproof paper, pour in the mixture and bake for 20-25 minutes. The brownie will still be soft once cooked.
Leave to rest in the baking tray for an hour or so before turning out and cutting.