Preheat the oven to 350 degrees. Spray cake pan generously with baking spray such as Pam for Baking. Place the prepared pan on a rimmed baking sheet.
Whisk flour, baking soda, cinnamon, ginger, cloves and salt together in a medium bowl. Set aside.
Combine butter, sugar, brown sugar and molasses together in the bowl of a stand mixer. Mix with the paddle attachment until light and fluffy, about 3 minutes. Add the egg and mix until thoroughly combined.
Turn the mixer speed down to low. Add one-third of the flour mixture followed by half of the buttermilk. Add the second third of the flour mixture followed by the remainder of the buttermilk. Finally, add the remainder of the flour mixture. Mix until everything just comes together.
Scrape the cake batter into the prepared pan and smooth out the top. Bake until golden brown and a tester inserted in the center of the cake comes out clean, about 35-45 minutes. Let the cake rest in the pan for 10 minutes and then carefully flip out onto a wire rack.
While the cake is cooling, make the icing: Whisk the powdered sugar, vanilla and 1 tablespoon of water together in a small bowl. Add additional water as necessary to create an icing that is a pourable consistency. Once the cake has completely cooled, drizzle the icing over the top of the cake. Slice and serve.