To make the blondies, beat the eggs and sugar in a large bowl using an electric whisk for 2-3 minutes or until pale and slightly fluffy. Add the melted butter and vanilla, and mix briefly to combine. Add the flour, baking powder and salt, and mix briefly into a soft batter. Add most of the white chocolate and cranberries, reserving a little of both for decoration. Scrape the batter into the prepared tin and spread into an even layer.