Preheat oven to 350°F. Spray an 8 x 8 baking dish with non-stick spray and set aside.
In a large bowl, use a hand mixer to beat together the butter and sugar until creamed and the texture is light and fluffy.
Mix in the vanilla.
Mix in the molasses and the egg until well combined. Set aside.
In another mixing bowl, whisk together the flour, salt, baking soda, ginger, cinnamon, nutmeg and allspice.
Add the dry ingredients into the molasses mixture alternating with the hot water and beating after each addition. Repeat until out of water and flour mixture.
Pour into the prepared pan and bake for 35-40 minutes or until toothpick inserted into the center comes out clean.
While the cake is cooling, make the frosting.
To make the Cream Cheese Frosting
To a large bowl (or the bowl of your stand mixer), add the room temperature cream cheese and butter and mix together until creamy and well combined. Mix in the vanilla. Add in the powdered sugar in small parts, mixing well between each addition. Do not over mix.
Frost the cooled cake and sprinkle with some nutmeg.
If you don't want to frost the cake, sprinkle with powdered sugar.
If frosted, store the cake, covered, in the refrigerator.
If sprinkled with powdered sugar, the cake can be stored covered at room temperature.
If you have any frosting leftover, cover and store in the refrigerator for up to 5 days.