Preheat oven to 350 degrees. Butter and flour a 9-by-9-inch cake pan; set aside.
In a small bowl, combine boiling water and baking soda; set aside. In a large bowl, sift together flour, ground spices, salt, and baking powder; set aside.
In an electric mixer with the paddle attachment, cream butter until light. Beat in brown sugar until fluffy. Next, beat in molasses and grated ginger, baking-soda mixture, and flour mixture. Finally, beat in eggs.
Pour the batter into your prepared pan. Bake the cake until a toothpick inserted in center comes out clean, (approximately 30 to 35 minutes). Let cool on a wire rack. Cut into squares. Serve with the Lemon Hard Sauce or a nice dusting of confectioners’ sugar.
For the Lemon Hard Sauce:
In a medium sized bowl, on medium-high speed beat the softened butter, lemon zest, and lemon juice until just creamy. Add the powdered sugar and vanilla into the bowl in small doses and beat until it is nice and fluffy.