01 - Preheat oven to 350°F. Grease and line a 9x9-inch baking pan with parchment paper.
02 - Whisk together flour, ground ginger, cinnamon, cloves, nutmeg, baking soda, and salt in a medium bowl.
03 - In a large bowl, cream unsalted butter and brown sugar until light and fluffy.
04 - Add eggs one at a time to the creamed mixture, beating well after each addition.
05 - Mix in molasses and vanilla extract until fully blended.
06 - Alternately add dry ingredients and whole milk to the wet mixture, beginning and ending with dry ingredients. Mix until just combined, avoiding overmixing.
07 - Pour batter into the prepared baking pan and smooth the surface evenly.
08 - Bake for 30 to 35 minutes or until a toothpick inserted in the center comes out clean.
09 - Allow to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Dust with powdered sugar and garnish with citrus zest if desired before slicing.