Fruit Preparation: Combine currants, raisins, sultanas, dates, apricots, cranberries, mixed peel, and the zests of one orange and one lemon in a large mixing bowl. Pour 175 milliliters of brandy or bourbon over the mixture, stir thoroughly, cover, and allow to soak overnight.
Preheating and Tin Preparation: The following day, preheat the oven to 150°C (130°C for fan ovens, gas mark 2). Prepare a deep 23cm cake tin by lining both the base and sides with a double layer of baking parchment. The parchment should extend a few centimeters above the rim of the tin.
Batter Preparation: In a large bowl, cream together the softened butter, dark muscovado sugar, and treacle using an electric whisk until the mixture is pale and creamy. Alternatively, a stand mixer may be used. Gradually beat in the eggs, one at a time, ensuring each is fully incorporated before adding the next. Regularly scrape down the sides of the bowl. In a separate bowl, sift together the plain flour, baking powder, mixed spice, ground cinnamon, and ground ginger. Gradually fold this dry mixture into the wet ingredients, then incorporate the ground almonds to form a uniform batter.
Combining and Baking: Fold the soaked fruit, along with any remaining liquid, into the batter. Transfer the batter into the prepared cake tin, smoothing the surface with the back of a spoon. Bake in the preheated oven for approximately 2 hours and 25 to 30 minutes. The cake is done when a skewer inserted into the center comes out clean. Should the cake begin to over-brown, cover it with foil.
Cooling and Storing: Allow the cake to cool completely within the tin. Once cooled, use a cocktail stick or skewer to prick small holes over the surface of the cake. Brush a small amount of brandy over the surface. Wrap the cake in baking parchment, followed by a layer of foil, and store in an airtight container. Feed the cake with 1-2 tablespoons of brandy weekly for three to four weeks, ceasing this process one week prior to icing. The cake can be stored in a cool, dry place for up to six months.