Preheat an oven to 350°F. Using the 1 teaspoon butter, grease a 10-by-15-inch baking pan.
In a large bowl, using an electric mixer on medium speed, beat the 1 cup butter and the sugars until light and fluffy Beat in the eggs one at a time, blending well. Add the orange zest, vanilla, and apricot brandy and beat to blend well.
In a medium bowl, combine the flour, baking powder, baking soda, cardamom, mace, apricots, currants, and pistachios and stir to mix well. Stir the flour mixture into the butter mixture and blend well.
Spread the batter evenly in the prepared pan and bake for about 20 minutes, or until a toothpick inserted in the center comes out clean. Transfer the pan to a wire rack and let cool about 15 minutes.
To make the icing: In a bowl, combine the confectioners’ sugar and orange juice and mix to a medium-firm consistency. Spread on the top of the still-warm, uncut cookies in the pan and let stand until the icing sets. Cut the cookies into 1½-inch squares.
To store, place in single layers, separated by sheets of waxed paper, in an airtight container. Store for 2 to 3 days, or freeze.