Preheat the oven to 150C/gas 2 and line the base and sides of a 23cm round tin or a 20cm square tin with a double layer of greaseproof paper. You’ll need the side lining to be a good 8cm higher than the tin.
If you’d like your cake to be particularly moist, blitz half the soaked fruit in a food processor to make a paste, and stir back into the rest of the fruit. In a large bowl, cream the butter and sugar until light and fluffy. Grate in the zest of your lemon and beat in the eggs, one at a time. Mix in the treacle. Sift the flour and combine with the spices and ground almonds. Mix into the butter mixture, alternating with the soaked fruit. Finally, fold in the walnuts. Spoon the mixture into the lined tin and bake in the oven for about 3 hours. Check after 2½ hours and then every 20 minutes, or until a skewer comes out clean.
As soon as the cake comes out of the oven, brush with a little more booze. Leave to cool in the tin for 5 minutes and then remove, placing it directly onto a large sheet of tin foil. Wrap it up twice to retain the heat for as long as possible. After a few hours, remove the foil and wrap the cake up again in a double sheet of greaseproof paper and a double sheet of tin foil, making sure you can access the cake from the top. Store in an airtight container for 2–12 weeks. During this time, feed the cake the alcohol of your choice by gently pouring it over the top and rewrapping.