Hermione refuses to eat after discovering that enslaved house-elves cooked her food. Ron has no such qualms and naughtily tries to tempt her with spotted dick.
Fill a large pot with water and place a rack or overturned shallow bowl in the pot. Bring to simmer. Grease a 2-quart heatproof bowl with a tight-fitting lid and set it aside.
Whisk together the flour, bread crumbs, sugar, baking powder, salt, and spices in a large mixing bowl. Rub in the butter until the mixture resembles coarse meal with some larger pieces of butter remaining. Toss in the raisins and currants or cranberries. Pour in the milk and fold it in until the mixture is uniformly moistened. Turn out the mixture into the prepared dish and press the top down with a spatula.
Cover the dish with the lid, making sure it is tightly sealed. Place it in the pot; the water should come halfway up the sides of the dish. Steam for 3 hours. Add water to replenish as necessary.
Remove the pudding, remove the lid, and invert it onto a plate. Serve warm with warm custard.
To make fresh bread crumbs, process 6 to 8 slices of fresh bread in a food processor or blender. There is no need to remove the crusts.