Preheat oven to 350 degrees F and grease 9-inch square baking dish with nonstick spray and line with parchment paper, leaving 2 inches overhanging on two sides.

Using electric mixture and large mixing bowl, beat butter and sugar until light and fluffy, scraping down sides of the bowl as necessary.

Add egg and molasses, mixing well between additions, until smooth and uniform.

In separate bowl, combine all-purpose flour, whole wheat flour, baking soda, cinnamon, ginger, cloves, nutmeg and salt.

Gradually add dry ingredients to butter mixture while mixing on low speed. Mix until just combined. Stir in water until smooth.

Transfer batter to prepared baking dish. Bake 30 to 45 minutes, until a toothpick in the center comes out mostly clean.

Cool in pan on wire rack for 10 minutes, then carefully transfer cake from pan to wire rack. Cool to room temperature before dusting with powdered sugar using a fine-mesh strainer.