Preheat the oven to Gas 4, 180°C, 350°F. Line a 20cm (8in) square cake tin with baking parchment.
Melt the chocolate in a bowl over a pan of barely simmering water. Stir well and cool slightly.
With an electric whisk, cream together the butter and sugar in a large mixing bowl then add the eggs, a little at a time, still beating.
Sift in the flour, add the slightly cooled melted chocolate, the macadamias and the cranberries. Gently fold everything together.
Pour the mixture into the tin, spread it out and bake on the centre shelf for 45mins until cooked on top but still soft in the center. Leave to cool in the tin, then remove and cut into 16 squares.
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