Preheat the oven to 180°C/356F/ Gas 4.
Grease and line a shallow, square cake tin.
Beat the eggs and sugars together in a bowl.
Over a pan of simmering water, Melt the chocolate with the butter in a heatproof bowl. When it is melted remove from the heat and stir into the egg and sugar mixture.
Gently stir in the flour then the marmalade and mix well.
Pour into the prepared tin and bake in the oven for 30-35 minutes.
Leave to cool in the tin for 10 minutes before turning out onto a wire rack to cool completely.
Cut into squares before serving.