Whisk 2 3/4 cups flour, 2 tablespoons gingerbread spice, 1 1/2 teaspoons baking powder and 1/2 teaspoon each baking soda and salt. In a separate bowl, beat 2 sticks softened butter and 1 2/3 cups light brown sugar with a mixer on medium-high speed until fluffy, 4 minutes. Beat in 4 eggs, one at a time, then beat in 2 teaspoons vanilla. Beat in 1/4 cup molasses on low speed, then beat in the flour mixture in three batches, alternating with 3/4 cup milk. Pour into a buttered and floured 10-cup bundt pan. Bake at 350˚ until a skewer inserted into the center comes out clean, 55 minutes to 1 hour. Let cool 10 minutes in the pan, then invert onto a rack to cool completely. Dust with confectioner’s sugar.