Preheat oven to 350 degrees
Melt butter over medium heat. Remove from the heat and allow to cool for a few minutes.
To a large mixing bowl add brown sugar and butter. Whisk together well before adding 2 large eggs, molasses and vanilla. Whisk until everything is fully incorporated.
To a separate bowl sift together the flour, baking powder, salt, ground ginger and cinnamon.
Add the dry ingredients to the wet in stages, folding in each round with a spatula.
Evenly spread into a parchment lined 9x9 pan and bake in the middle rack for 30-35 minutes.
Rest for at least 2 hours. Sprinkle with powdered sugar, cut into 9 squares and serve!