For the crema pasticcera: Scald the milk in a medium saucepan with the lemon rind and vanilla extract over medium-low heat. In a separate bowl, whisk the egg yolks and sugar until the mixture is pale and creamy. Add the flour and whisk until smooth. Slowly pour a little of the hot milk into the egg yolk mixture, whisking to temper the yolks, then add remaining hot milk whisking constantly to prevent the eggs from cooking.
Strain the mixture back into the saucepan and return to medium-low heat. Whisk constantly until it thickens and just begins to boil — about 10 minutes. Remove from the heat. Pour the custard into a bowl, and place a piece of parchment paper directly on the custard surface and allow to cool. Set aside.
To make the syrup: In a small saucepan, combine the water and sugar. Bring to a boil, then reduce the heat and simmer until the sugar dissolves completely — 2 to 3 minutes. Remove from the heat and stir in the Alkermes. Set aside to cool.
You will want to use a glass trifle bowl or eight wine glasses to serve the Zuppa Inglese so that the layers are visible. I use straight-sided wine tumblers.
To assemble: One by one, dip both sides of the Savoiardi biscuits into the cooled syrup and make a layer in the bottom of your bowl or individual glasses. Don’t let them soak in the syrup; a long dip is all you need. If using individual glasses, you will need to cut the Savoiardi into pieces to fit — about 1 1/2 biscuits per layer.
Spoon and spread half of the cooled Crema Pasticcera evenly over the biscuits and then repeat the process with another layer of dipped biscuits, followed by the remaining crema. Top with whipped cream.
Cover the dish and refrigerate for at least 8 hours, or overnight, to allow the biscuits to soften and the flavors to fully develop. Sprinkle the top lightly with ground cloves for serving.