-garnish Pour cream into a well-chilled mixing bowl. Beat in an electric mixer fitted with chilled beaters or whip attachment. Stir in the confectioner's sugar and cocoa and beat on medium speed until the cream begins to thicken. Add the coffee zest and liqueur. Continue whipping until cream reaches the soft peak stage, and remove from the mixer. Finish beating by hand using a wire whisk, whipping until cream is quite thick but not grainy. Refrigerate. Note: to make coffee zest, add 3 parts coffee crystals to 1 part boiling water. To assemble the cake, split each layer into halves. Set the first layer on a serving plate, top side down. Fit a 14-inch pastry bag with a large no. 5 plain tube, and fill it 1/3 rd full with mocha whipped cream. Starting 1/2 inch from the edge, pipe a circle of cream around the top of the layer. Fill center of the circle with additional cream, smoothing surface with a large metal offset spatula. Repeat with the second and third layers, placing them cut side up. Arrange the top layer cut side down, aligning layers so the sides of the cake are even. Empty the remaining whipped cream into the pastry bag. Pipe 1/2 inch whipped cream dots on the top layer, beginning at the outer edge. Each dot should touch the preceding one, forming a ring. Continue working toward the center of the cake until the entire surface is covered. Place 1/2 tsp cocoa in a very fine mesh strainer. Gently tap the strainer over the surface of the cake to give it a light dusting of cocoa. Place the cake in the refrigerator uncovered to chill, but remove from refrigerator at least 1 hour before serving. Storage: Store leftover cake in the refrigerator under a foil tent. This cake will keep for up to three days.