Put the dried fruit in a bowl and cover with 200ml boiling water. Leave to soak, uncovered, overnight.
Sift the flour and spices into a large mixing bowl.
Add the breadcrumbs, shredded suet, grated chocolate, grated apple, brown sugar, mixed peel, almonds and citrus zest.
Mix well with your hands to ensure everything is fully blended together.
Add the soaked fruit, treacle, brandy and beaten egg and stir well.
Grease the pudding basin with a little butter. Cut a small circle of greaseproof paper and place on the bottom of the bowl – this will help with turning the pudding out.
Pack the pudding mixture in the bowl, pressing it down with your hands.
Cut a piece of greaseproof paper, a few inches bigger than the rim of the bowl. Fold a pleat into the centre and use an elastic band to secure it over the pudding bowl.
Cover the top with a piece of tin foil then tie it tightly with string. Make a loop of string across the top, to fashion a handle, so the pudding can be easily lifted.
Place a jam jar lid in the bottom of your slow cooker and position the pudding on top. Fill the slow cooker with boiling water to come up about 2/3 up the side of the pudding basin.
Cover and cook on high setting for four hours.
Lift the pudding out of the slow cooker keeping the greaseproof paper on – store until Christmas.
On Christmas Day, steam the pudding for two hours and then carefully turn onto a deep plate.
If you want to light the pudding, heat 80ml brandy in a small saucepan and light it. Carefully pour the lighted brandy over the pudding and serve as soon as the flames go out.