- Butter a 4-cup (1 litre) heat-resistant bowl. Layer a sheet of foil (shiny side up) on top of a sheet of parchment paper to make a 17 x 12-inch (45 x 30 cm) rectangle. Fold the sheets together with a pleat in the centre in a Z shape to allow the paper to expand while cooking.
- In a small bowl, combine the flour, baking powder and salt. Set aside.
- In a large bowl, combine the brown sugar, bread crumbs, butter and spices. Add the dried fruits, candied citrus peel, almonds, apple and citrus zests.
- In another bowl, whisk together the eggs and 2 tbsp (30 ml) of the brandy. Add to the dried fruit mixture and mix until combined. Stir in the flour mixture. Transfer the batter to the buttered bowl. Cover with the folded paper and secure it with twine or an elastic band around the top of the bowl.
- Place the bowl on a tea towel inside a large pot. Add enough water to the pot to reach halfway up the bowl. Cover and cook on the stovetop for 4 hours at medium-low, keeping the water at a gentle simmer. Remove the bowl from the water and let cool on a wire rack.
- Remove the twine and paper. Sprinkle with the remaining brandy. Cover with a new sheet of parchment paper secured with string and let macerate in the bowl for 7 days in a cool, dark spot (a pantry works well). The plum pudding will keep in an airtight container for 1 month at room temperature.
- When ready to serve, place the bowl on a tea towel inside a pot. Add enough water to the pot to reach halfway up the bowl. Cover and simmer for 2 hours, keeping the water at a gentle simmer. Remove the bowl from the water. Remove the paper and turn the pudding over onto a serving plate.
- Meanwhile, in a bowl, cream the butter and brown sugar with an electric mixer until very smooth, about 5 minutes. Stir in the brandy. Serve the sauce with a slice of the warm plum pudding. Decorate with berries, if desired.