1.Preheat oven to 180°C (160°C fan forced). Grease and line the base and side of six 1-cup (250ml) metal diarole moulds.
2.Make mandarin jam. Place mandarin and the water in a medium saucepan, simmer, uncovered, stirring occasionally, for 1 hour or until mandarin is tender. Add sugar, stir until sugar dissolves. Simmer over medium heat for 10 minutes or until mixture is the consistency of soft jam.
3.Beat butter, extract and sugar in a small bowl with an electric mixer until thick and creamy. Beat in eggs one at a time. Transfer mixture to a medium bowl, stir in sifted flour and milk, in two batches.
4.Spoon mandarin jam into moulds, top with pudding mixture, tap moulds gently to level mixture. Cover each mould with greased foil, secure with string. Place moulds in a large roasting pan, pour enough boiling water into the pan to come one-third of the way up sides of the moulds.
5.Bake puddings 40 minutes or until a skewer inserted into the centre comes out clean.
6.Meanwhile, make custard. Bring cream and milk almost to the boil in a medium saucepan. Meanwhile, whisk egg yolks and sugar in a medium bowl until thick and creamy, gradually whisk in hot milk mixture. Return mixture to same pan, stir over low-medium heat until mixture thickens enough to coat the back of the spoon (do not allow to boil). Stir in liqueur.
7.Turn hot puddings out onto individual plates, serve with warm custard.