Combine the melted butter, brown sugar, and molasses in a large mixing bowl and whisk until homogenous.
Add the egg, vanilla, and fresh ginger (if using), and mix to combine.
In a separate bowl sift together the flour, ginger, cinnamon, all spice, cloves, baking powder, and salt. Add the dry ingredients to the wet ingredients and fold to combine. Do NOT over mix.
Transfer the batter into the prepared pan and spread into an even layer. Bake at 350°F for 20 to 30 minutes or until the edges are set, but the middle is still slightly gooey.
While the blondies cool, make the cream cheese icing. Beat the softened butter and cream cheese together until homogenous, about 2 minutes. Add the powdered sugar, cinnamon, vanilla, and salt and beat until fluffy, about 2 minutes.
Once the blondies are cool, Spread with the cream cheese icing. Sprinkle with cinnamon sugar or leave plain! Slice and serve!