Heat the olive oil in a wide shallow pan, add the rice and toss to coat in the oil.
Add the milk and cook slowly, stirring until the milk is absorbed and the rice is soft.
Stir in the chocolate and leave to cool.
Knead the marzipan with the icing sugar and food colouring.
Roll out on a surface dusted with icing sugar to to 25 x 9 cm.
Place on a sheet of non-stick baking paper 3 Spread the risotto evenly on the rolled-out marzipan and press on firmly, leaving about 1 cm free on the narrow side.
Lay the melon down the middle of the rice and roll up the marzipan and rice from the long side to form a sushi roll, using the paper to help you.
Chill for 2 hours.
Remove the paper from the roll and cut into 2 cm lengths.
Mix the candied orange peel with the orange juice and put into a small bowl.
Serve with the sweet sushi rolls.