Preheat the oven to 350 degrees F. and position the baking rack to the lower portion of the oven. Line an 8x8-inch square baking pan with parchment paper. Set aside.
In a medium bowl, whisk together the sugar, melted butter, molasses, and egg until combined. Set aside.
In a separate medium bowl, whisk together the flour, baking soda, salt, ground ginger, cinnamon, cloves, nutmeg, and allspice until combined.
Stir the flour mixture into the sugar mixture until it comes together. Carefully add the boiling PUR filtered water and whisk until blended. Fold in the chopped candied ginger until evenly distributed.
Pour the batter into the prepared baking pan and place into the oven to bake for 35 to 40 minutes or until a cake tester comes out clean. Allow the cake to cool in the pan on a rack for 10 to 15 minutes before transferring to a wire rack to cool completely.
Cut the cake into 8 even squares and serve warm with a hot cup of coffee. Store in an airtight container at room temperature.