Preheat oven to 350. Grease and flour a 10 inch tube pan. Heat liqueur and instant coffee in a small saucepan and stir until coffee dissolves. Add enough milk to equal 1 cup liquid and set aside. In a small bowl, whisk together cocoa powder and confectioners' sugar and set aside. In a large electric mixer bowl, beat butter until very soft. Add granulated sugar, vanilla and salt and beat until light. Add eggs one at a time and beat well after each addition. In a medium bowl, stir together flour, baking powder and soda. Fold flour mixture into butter mixture alternately with coffee liquid. Turn half batter into prepared pan and smooth surface. Using back of kitchen teaspoon, make an indentation 1/2 inch deep in batter. Spoon cocoa-confectioners' sugar mixture into depression. Spoon remaining batter over top of cocoa mixture. Using broad side of dinner knife, cut down through batter to bottom of pan, moving knife in zigzag pattern to create a marbled effect. Smooth batter surface with back of spoon. Bake 50-55 minutes or until toothpick inserted in center comes out clean. Remove cake from oven and cool in pan on rack 15 minutes. Run knife around center tube and outer edge of pan. Carefully invert onto rack and cool to room temperature. Dust lightly with confectioners' sugar. If you don't want to use alcohol in this recipe, just use strong coffee.

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