Preheat the oven to 350ºF.  Butter and flour a 9-inch square baking pan. Using a hand-held electric mixer set at high speed, beat the butter until creamy, about 1 minute. Add the sugar and beat until light in color and texture, about 2 additional minutes. Beat in the eggs and orange zest. Sift the flour, baking soda, ginger, cinnamon, allspice, nutmeg, salt, and cloves onto a piece of waxed paper. In a 2-cup glass measuring cup, combine the molasses and boiling water. Alternately in thirds, beat in the flour and molasses mixtures. Transfer the batter to the prepared pan. Bake until a toothpick inserted in the center of the cake comes out clean, and the cake is shrinking from the sides of the pan, 40 to 50 minutes. Let stand on a wire cake rack for 5 minutes. Place the confectioners sugar in a sieve and dust over the top of the cake. Serve the cake warm or completely cooled. Makes 12 to 16 servings.