Prepare the dry ingredients by whisking together flour, ground ginger, cinnamon, baking soda, and salt in a large mixing bowl and set aside.

Combine the wet ingredients by beating together softened butter, brown sugar, and molasses until smooth, then add eggs one at a time until fluffy.

Mix the dry ingredients into the wet mixture gently until just combined. Be careful not to overmix.

Preheat oven to 350°F (175°C) and prepare an 8x8-inch baking dish by greasing or lining it with parchment.

Pour the batter into the prepared baking dish and bake for 25-30 minutes, or until a toothpick inserted comes out clean.

Allow to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely before frosting.

Prepare the frosting by mixing cream cheese and powdered sugar until smooth, then frost the cooled bars and decorate as desired.