Preheat your oven to 325°F (160°C). Grease and line a 9-inch (23cm) round cake tin with parchment paper.
In a large bowl, cream together the softened butter and brown sugar until light and fluffy.
Beat in the eggs one at a time, ensuring each is well incorporated before adding the next.
In a separate bowl, sift together the flour, baking powder, salt, and spices.
Gradually add the dry ingredients to the wet mixture, mixing well after each addition.
Stir in the Irish whiskey.
Fold in the mixed dried fruit, chopped nuts, orange zest, and lemon zest until evenly distributed.
Transfer the batter to the prepared cake tin and smooth the top.
Bake in the preheated oven for approximately 2 to 2.5 hours or until a skewer inserted into the center comes out clean.
While the cake is still warm, make small holes with a skewer and drizzle the additional Irish whiskey over the top for soaking.
Allow the cake to cool completely in the tin before removing.
Once cooled, you can decorate the cake with marzipan and icing if desired.
Enjoy your delicious Irish Christmas Cake!