In a mixing bowl, use an electric mixer or a hand mixer to cream together the sugar and softened butter. Beat in the egg, and then stir in the molasses.
Stir the flour, baking soda, cinnamon, ginger, cloves, nutmeg, and salt into the wet mixture. Mix on low. Stir in the hot water.
Pour the batter into the cake pan. Bake for 40-50 minutes, or until an inserted knife or toothpick comes out mostly clean. Let cool. Once cool, invert the cake onto a plate or rack.
Put the powdered sugar into a small bowl, and slowly add very small amounts of water, until a syrupy consistency is achieved. Drizzle over the cooled cake.
Notes
If using a 9" square pan, reduce bake time to about 35 minutes.