Preheat your oven to 350°F (175°C). Grease and flour a 9-inch (23cm) round cake pan.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt, cinnamon, nutmeg, cloves, and allspice until well combined.
Cut the softened butter into small pieces and add it to the dry ingredients. Using your hands or a pastry cutter, work the butter into the flour mixture until it resembles fine crumbs.
In a separate bowl, whisk together the buttermilk, eggs, and vanilla extract.
Gradually pour the wet ingredients into the dry ingredients, mixing until just combined. Be careful not to overmix; a few lumps are okay.
Gently fold in the raisins, currants, and chopped candied peel, if using.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake in the preheated oven for about 40-45 minutes or until a toothpick inserted into the center of the cake comes out clean.
Remove the cake from the oven and let it cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
Once the cake has cooled, dust the top with confectioners' sugar for an elegant finishing touch.
Slice and serve this delightful Authentic Irish Spice Cake with a cup of tea or coffee, and savor the rich flavors and cultural heritage of traditional Irish baking.
Enjoy this classic Irish spice cake, and share its delightful taste and history with your family and friends. Happy baking!