Place mandarins in a medium saucepan and cover with cold water. Place a saucer over the top to keep mandarins submerged. Place over high heat and bring to the boil. Remove from heat and drain. Return mandarins to the saucepan and repeat the process 2 more times (this will reduce the bitterness of the rind). Return mandarins to the pan and cover with cold water. Place over high heat and bring to the boil. Reduce heat to medium-low and cook, covered, for 1 hour or until very tender. Drain well. Set aside for 1 hour to cool.

Preheat oven to 180°C. Grease and line the base and side of a round 17cm (base measurement) cake pan with baking paper.

Place the pistachios in the bowl of a food processor and process until very finely chopped. Set aside. Cut mandarins into quarters and remove any pips. Place in the bowl of a food processor and process until smooth.

Use an electric mixer to whisk eggs and sugar in a large bowl until thick and pale. Add mandarin mixture, pistachio and baking powder and use a metal spoon to fold until just combined. Pour into the lined pan and bake in oven for 1 hour or until a skewer inserted in the centre comes out clean. Remove from oven and set aside to cool in the pan.

Top with thinly sliced glace orange rind, if desired. Serve with thick cream.