Preheat the oven to 180°C/Gas Mark 4. Use the butter to grease a 1-litre (1¾pts) baking dish.
Heat 300ml (10fl oz) water in a saucepan with half the caster sugar, the cinnamon stick and 5-spice powder. When the sugar has dissolved, add the plums and simmer gently for 5 minutes.
Meanwhile, use a whisk to beat together the eggs, flour, salt, milk, single cream, vanilla extract and brandy. Add the remaining sugar. Allow a few minutes for the sugar to dissolve, then stir in the almonds.
Use a slotted spoon to transfer the plums from the cooking liquid to the baking dish. Pour in the batter and bake for 45-50 minutes until golden brown. Cool for a few minutes.
Meanwhile, whip the cream in a chilled bowl until it holds its shape, then whisk in the sugar, brandy and vanilla extract. Serve the plum pudding sprinkled with icing sugar and a few extra almonds, accompanied by the brandy cream.