Place the egg yolks and sugar in the top of a double boiler or a large heat proof bowl over a saucepan that has an inch or two half of water, making a kind of double boiler.
With a wire whisk or with the whisk attachment of a hand mixer beat the egg yolks with the sugar until they are completely combined and the mixture has a glossy appearance.
Turn on the flame, moderately high until the water boils, then reduce the heat to a simmer and keep whisking. Make sure the bottom of the double boiler or bowl does NOT touch the water. As the water heats the egg mixture it will begin to thicken. As it thickens it will grow in volume. Keep whisking. This takes a little patience but it is well worth the effort. Your zabaglione will be done when it is thick, frothy and holds ribbons form as you whisk it. The temperature reaches 145 to 150 degrees F, on an instant-read thermometer.
Take the zabaglione off the heat and continue to whisk. Add the Mascarpone to the whipped yolks and beat until combined. Add the Amaretto liqueur. Cover with plastic wrap and let cool completely.
In a separate bowl, that has been chilled along with the beaters, whip the cream to stiff peaks taking care NOT to overbeat and make butter.
Gently fold in the whipped cream into the zabaglione mixture and set aside.
Put the espresso in a food safe spray bottle. Spray the white cake with the espresso making sure you don't oversaturate. The ⅓ cup of espresso should be just right. If you don't have a spray bottle you can do it by hand-- be sure you don't get too much in one spot.
Spread the Zabaglione Cream evenly over the top of the espresso-sprayed cake.
Dust the top with cocoa powder and garnish with crushed chocolate chips.