2Combine egg yolks, instant dark roast coffee, marsala wine, and sugar in a metal bowl and whisk together until smooth.
3Place bowl in the top of a double boiler over lightly simmering water. Whisk constantly until mixture thickens and drippings from the whisk form ribbons on the surface that are visible for 1/2 second to 1 second, about 10 minutes. If you are "brave", you can set the bowl directly over medium-low heat and thicken the egg cream that way, but you have to be careful so you don't end up with scrambled eggs. This last method is slightly faster and will take about 6 to 7 minutes.
