Preheat your oven to 350℉. Prepare a 9-inch diameter cake pan by greasing and lightly flouring it.
In a large bowl, use an electric mixer to cream together the butter, sugar, and egg until well blended.
Carefully beat in the molasses, mixing until everything is smoothly combined.
In a separate medium bowl, whisk together the flour, baking soda, ginger, salt, and nutmeg.
Add the dry ingredients to the wet mixture in two parts, alternating with the hot water.
Pour the batter into the prepared cake pan, using a spatula to spread it evenly.
Bake in the preheated oven for 25 to 30 minutes.
Once baked, allow the cake to cool in the pan on a wire rack for about 15 minutes.
After cooling, turn the cake onto a wire rack.
Before serving, dust the cake with powdered sugar for a beautiful finish.
