To Make the Chocolate Ganache

1. Put the chocolate chips for the ganache in a heat proof bowl. Set aside.
2. In a small saucepan, heat heavy whipping cream for ganache until it comes to a boil, then pour over the chocolate chips.
3. Cover and allow hot cream and chocolate chips to sit for about 5 minutes, then whisk until smooth. Set aside to cool a bit and thicken.

To Make the Mocha Mousse

1. Prepare a 9-inch springform pan by lining the sides with parchment paper or an acetate collar that sticks about an inch above the sides of the pan.
2. Pour the milk in a small measuring glass and microwave it to bring it to a boil, then dissolve powdered espresso in the milk. Allow to cool.
3. Beat softened cream cheese and sugar for mocha mousse together in a large mixer bowl until smooth.
4. Slowly add espresso mixture to cream cheese mixture and beat until smooth. Set cream cheese mixture aside and make whipped cream.
5. Whip heavy whipping cream on high until it begins to thicken. Add vanilla extract and powdered sugar and continue to whip on high until stiff peaks form.
6. Carefully fold whipped cream into espresso cream cheese mixture.

To Assemble the Icebox Cake

1. Place a single layer of chocolate wafer cookies on the bottom of the pan, then top with about 1/3 of the espresso mixture (about 2 1/3 cups). Spread about 1/3 of the ganache (about 1/2 cup) evenly on top of the espresso mixture.
2. Repeat previous step two more times so that you have 3 of each layer. Refrigerate until firm, 4-5 hours or overnight.

To Make the Whipped Cream Topping and Finish the Cake

1. Once firm, remove icebox cake from pan.
2. Whip heavy whipping cream on high until it begins to thicken. Add vanilla extract and powdered sugar and continue to whip on high until stiff peaks form.
3. Pipe the whipped cream around the top edge of the cake, then drizzle with chocolate sauce. Finish off cake with chocolate covered espresso beans, if desired.
4. Refrigerate until ready to serve. Best if eaten within 3-4 days.