This classic Italian dessert is usually spooned into glasses and served warm, but it also makes a great sauce for ice cream!
In the top of a double boiler, beat egg yolks with sugar until the mixture is pale yellow and creamy
In the bottom of the double boiler, bring 2"-3" of water to a simmer (not a boil)
Place the egg mixture over the simmering water, making sure the bottom of the pan doesn't touch the water. Whisk until it begins to thicken, about 5 minutes. Be careful not to beat too long or you will cook the eggs.
Remove the top of the double boiler from the heat and whisk in the coffee, coffee liqueur, nutmeg and grated lemon rind. Return the pan to the double boiler and whisk until the mixture increases in volume and becomes light and fluffy, about 3-5 minutes.
Pour into coffee mugs and decorate with whipped cream and shaved semi-sweet chocolate.