Preheat the oven to 325 degrees Fahrenheit.
Grease a 9x13 baking pan and line it with parchment paper.
In a saucepan, combine water and raisins and bring it to a gentle boil. Let it simmer for 10 minutes.
Add shortening to the mixture and let it cool to room temperature.
Sift together sugar, soda, flour, cloves, cinnamon, nutmeg, allspice, and salt.
Add the sifted ingredients to the cooled raisin mixture along with the beaten egg and nuts (if using). Fold gently until the flour is just incorporated into the batter. Avoid over-mixing.
Pour the batter evenly into the prepared pan.
Bake for 30-35 minutes or until a wooden toothpick inserted into the center comes out clean.
Let it cool completely and, if desired, ice with frosting.