1. Add the dried fruit, lemon zest and juice and rum to a large bowl and mix well. Cover and leave to soak overnight.
2. The next day, steam or simmer the cavolo nero for a few minutes until tender. Drain and refresh by running under cold water. Squeeze out any excess moisture then chop finely. Add the chopped cavolo nero to the bowl of dried fruit, along with the almonds and mix well.
3. Grease the 900ml pudding basin with butter.
4. Cut two pieces of greaseproof paper, at least twice as wide as the pudding basin. Layer the two pieces, then fold to create a 1 inch pleat down the centre. Butter the top layer.
Cut a piece of foil at least twice the size of the pudding basin. Pleat, as before.
5. Put the butter and sugar into a large bowl and cream together with an electric mixer for a few minutes until light and fluffy.
6. Gradually beat in the egg, a little bit at a time and beating well between each addition.
7. Sift the flour and mixed spice into the bowl of creamed butter and sugar, then add the breadcrumbs and soaked fruit mixture (including all the liquid). Stir well to combine.
8. Spoon the mixture into the prepared pudding basin and level the top. Place the greaseproof paper on top, butter side facing the pudding, trimming a wide edge around the basin. Cover with the foil, tucking the ends around the rim of the basin, enclosing the greaseproof paper. Tie the foil securely around the rim with the string.
9. Place the pudding into a large pan with enough simmering water to come halfway up the sides of the basin. Cover the pan with a lid and steam for 6 hours, topping up the water as needed.
10. Carefully remove the pudding from the pan and allow to cool. Remove the string, foil and greaseproof paper, and turn it out onto a plate.
Developed by Veggie Desserts on behalf of Discover Great Veg’ www.discovergreatveg.co.uk