In a large mixing bowl, beat 1/2 cup of softened unsalted butter and 1/2 cup of brown sugar using an electric mixer on medium speed until light and fluffy, about 2-3 minutes.

Incorporate 1 large egg, 1/2 cup of milk, and 1/2 cup of molasses into the butter-sugar mixture. Mix on low speed until just combined.

In a separate bowl, whisk together 1 1/3 cups of all-purpose flour, 1 heaping teaspoon of cinnamon, 1/2 teaspoon of baking soda, 1/2 teaspoon of baking powder, 1/2 teaspoon of salt, 1/2 heaping teaspoon of ground ginger, and optionally, 1/2 teaspoon of nutmeg.

Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined.

Preheat your oven to 350°F (175°C). Pour the gingerbread batter into a greased 8x8-inch square baking pan and smooth the top. Bake for 20-25 minutes.

Once baked, let it cool in the pan for about 10 minutes and then transfer it to a wire rack to cool completely.

Spread a batch of cream cheese frosting over the cooled cake and top with Christmas sprinkles for decoration.