1 orange, zest only, grated, plus extra for serving
Preheat the oven to 180C/350F/Gas 4. Grease and line a 24cm/10in loose-bottomed cake tin with greaseproof paper.
Place the milk, vanilla pod, lemon zest and sugar in a large saucepan and bring to the boil. Add the rice and simmer on a medium to low heat for about 20–25 minutes, until the rice is al dente and has absorbed the milk but still has a creamy consistency. Remove from the heat and allow to cool. Remove vanilla pod and lemon zest.
In a bowl, whisk the egg yolks and liqueur until creamy. In another bowl, whisk the egg whites until stiff peaks form when the whisk is removed.
Add the egg yolk mixture to the cooled rice, then fold in the stiffened egg whites, followed by the raisins and orange zest. Pour in the prepared tin and bake in the oven for one hour. Serve warm or cold, sprinkled with a little extra orange zest to finish.