Preheat oven to 170°C (150°C fan oven) mark 3. Grease and line a 20.5cm (8in) loose-based cake tin with greaseproof paper. Soak the raisins in a bowl with the rum and set aside.
Put 175g butter into a bowl. Using an electric beater, beat in sugar, one large spoonful at a time, until light and fluffy. Next, beat in the eggs, a little at a time, then add the ground almonds and mix well. Stir in the soaked raisins. If the mixture looks curdled, leave for 5 minutes to allow the almonds to swell, and then stir again.
Fold in the flour, mixed spice and orange zest with a large metal spoon. Spoon the mixture into the prepared tin and smooth the top. Bake for 50min-1hr or until a metal skewer inserted into the middle comes out clean. Leave cake to cool in the tin for 10min, then turn out onto a wire rack to cool completely.
Carefully turn cake upside down, put on a serving plate and remove greaseproof paper.
Feeding the Cake: depending on how early you make this cake you might need to “feed” it with some alcohol to keep it moist. With a skewer, add some very small holes to the surface of the cake and gently pour in some rum or brandy until it soaks in. Wrap the cake carefully in greaseproof paper and keep in a tin until you are ready to decorate.
Decorating the Cake: A simple layer of white fondant icing with a pretty ribbon will always look well and is one of the easiest option. If your Christmas is not complete without Marzipan remember to cover the cake with some warmed Apricot Jam in order to ensure that the Marzipan stays on properly.