Butter the slow cooker all over the base and half way up the sides. Heat the milk to a simmer. Mix the pudding rice and the milk and pour into the slow cooker. Add the orange zest, and spices. Cook for 4 hours on low and stir once or twice if you can. If after 3 hours the rice pudding is beginning to stick to the base of the cook, add a splash of water. The rice will be tender when cooked. Add 100ml milk to loosen the pudding, if necessary.

Serve topped with orange segments and honey, fruit and raisins, if you like.