Preheat oven to 350°F. Spray a 9x13 baking dish with non-stick cooking spray.
In a large bowl, cream together the butter, brown sugar, and molasses using an electric mixer.
Beat in the eggs and vanilla.
Stir in the flour, ginger, baking powder, baking soda, and salt until just combined. Fold in the chocolate chips. Batter will be very thick.
Use a rubber spatula to spread the mixture into the prepared baking dish. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
Cool completely before sprinkling with powdered sugar and serving.