Add all ingredients to a bowl, stir to mix well, cover and leave at room temperature for 24 hours.
Mix the dry ingredients:
Add the flour, baking powder, nutmeg, allspice and breadcrumbs to a separate bowl. Mix well, set aside.
Mix the wet ingredients:
To a separate large mixing bowl, whisk the butter with the brown sugar, egg, and egg yolk together until smooth. Stir in the fruit marinade (and any brandy that didn’t get soaked up by the fruit) until well mixed. Add half the dry ingredients, stir to mix well. Add the remaining half and stir until there is no visible flour. You can cover it tightly at this point and keep until you want to steam (to let the flavors blend). Or, you can steam right away, then wrap and keep until Christmas.
Add parchment paper to a 1 liter/1 quart (6 inches/15 cm x 4 inches/10 cm) tall basin pudding dish. Pack the pudding mix into the bowl so it’s dense without gaps. Cover with parchment paper and 2 layers of foil. Tie tightly with string.
Steam:
Place a steam riser/trivet (or jam jar lid) onto the bottom of a tall pan with a lid. Place the bowl on top of the riser/trivet and fill with water until it reaches halfway up the bowl, place the lid on the pan. Bring the water to a light simmer/bubble and simmer for 7 hours. Check the water level every couple of hours.
When done, remove from the steam bath and allow to cool in the bowl until you can handle. Remove the string, foil and parchment. Place a plate on top of the bowl and flip the pudding. Allow to completely cool and eat immediately or wrap well and refrigerate.
The night before you’re serving leave on the counter at room temperature, still wrapped. Place (wrapped) in a 300°F/150°C oven for 30-45 minutes. Or steamed the same way it was cooked for 45 minutes.
For the brandy sauce:
Add the butter to a saucepan over medium heat. When melting and bubbling, stir in the flour. Slowly add the milk while stirring until there are no lumps, stir in the cream and sugar. Cook until thicken. Stir in the brandy, serve warm.