01 - Preheat oven to 350°F. Grease and line an 8-inch square baking pan with parchment paper.
02 - Whisk together flour, ground ginger, cinnamon, cloves, nutmeg, baking soda, and salt in a bowl.
03 - In a large bowl, beat softened butter with brown sugar until light and fluffy.
04 - Incorporate molasses and egg into the butter mixture, blending until smooth.
05 - Add the flour mixture in three portions, alternating with milk, starting and ending with flour. Mix gently until just combined.
06 - Pour batter into the prepared pan, smoothing the surface. Bake 22–25 minutes until a toothpick comes out clean.
07 - Allow to cool completely on a wire rack while still in the pan.
08 - Whisk powdered sugar, 1 tablespoon milk, and vanilla until smooth. Add more milk if necessary to achieve a thick but pourable texture.
09 - Spread icing evenly over cooled gingerbread. Let set for 15 minutes before cutting into 16 squares.