Prepare the mould. Ca. 2⁄3 Mix orange zest with 2 tablespoons of sugar. Roughly chop the chocolate. Place in a bowl with marshmallow cream and the rest of the zest.
Bring butter, cream and 250 g sugar to the boil. Simmer for about 5 minutes and add to the fluff mixture. Stir with the whisks of the mixer for 1-2 minutes until the chocolate has melted. Immediately smooth it down in the mould.
Break the meringue into large pieces, place on top and press down lightly. Sprinkle with orange sugar. Chill for at least 6 hours.
Lift fudge out of the mould and cut into cubes.