For the topping (we ommited this part):
Preheat oven to 150 °C. Grease and line (with parchment or wax paper) the base of an 20cm round deep cake pan (we used a loaf pan).
Put the butter, dried fruit, orange zest and juice, sugar and Guinness in a large pan. Bring slowly to the boil, stirring until the butter has dissolved, then simmer for 15 minutes.
Cool for 10 minutes, then stir in the baking soda. The mixture will foam up, but don't worry this is just the baking soda doing its work.
Stir the beaten eggs into the pan, then sift in the flour and spice and mix well.
Pour into the prepared pan, smooth the top with the back of a spoon and sprinkle with sliced almonds and demerara sugar (we ommited this).
Bake for 1 1/4 to 1 1/2 hours until a skewer or toothpick inserted in the center of the cake comes out clean.
Cool cake in the pan for 15 minutes; then turn out and remove the paper and leave to cool completely on a wire rack.