Preheat oven to 350°F. Grease and flour two 9-inch cake pans, line with parchment paper and set aside until ready to use.
In a medium bowl whisk together all-purpose flour, baking powder, baking soda, cinnamon, ginger, and Kosher salt. Set aside until ready to use.
Place the butter in a large mixing bowl and beat until smooth. Then, add the dark brown sugar and beat until fluffy.
Add the molasses, vanilla extract, and eggs, beat until well combined.
Scrape down the sides of the bowl. Add the flour mixture and water alternately, beginning with the flour mixture, about a cup at a time. And ending with the water, about ⅓ of a cup at a time. Scrape the bowl after each addition.
Use a large ice cream scoop to evenly divide the batter between the two prepared pans. Use a silicone spatula to smooth the batter into an even layer. Bake in the preheated oven for 35 minutes, or until a toothpick inserted in the center comes out clean.
Remove the pans from the oven and place the pans on a wire cooling rack. Let the cakes cool in the pans for 20 minutes. Then carefully remove them from the pans and allow them to cool completely, right side up, on cooling racks. If the cakes are upside down, the tops will stick to the cooling racks and damage the cakes.