Layers of alchermes-soaked sponge cake with custard and chocolate cream is Italy's trifle. This colorful mediterranean dessert is a family tradition across central Italy.
Cut the sponge cake into 1/2-inch slices. Set aside on a tray.
In a saucepan, whisk egg yolks and sugar over medium-low heat until pale, then slowly incorporate flour and lemon zest.
Heat milk to just below boiling, then gradually pour into the egg mixture while whisking constantly to prevent scrambling.
Return the saucepan to low heat, stirring steadily until the custard thickens, about 7–8 minutes; do not let it boil. Remove from heat and stir in vanilla extract.
Transfer half the hot custard to a bowl. Add the chopped dark chocolate to it and stir until melted and glossy, forming the chocolate cream.
Pour the alchermes liqueur into a shallow dish. Briefly dip each sponge cake slice, ensuring even soaking without oversaturating.
Layer soaked sponge cake in a glass trifle dish. Cover with half the plain custard, then add another soaked cake layer.
Spread the chocolate cream over the next layer, then add a final layer of soaked sponge and finish with the remaining custard.
Chill thezuppa inglese for at least 4 hours; this allows flavors to meld and cake to set.
Before serving, optionally top with extra grated chocolate or a sprinkle of more alchermes for fragrance.