Place the cornstarch, salt, half and half and 1/3 cup whisky in a heavy-bottomed 2-quart sauce pan over medium-low heat. Stir everything together until the cornstarch dissolves, about 1 minute. Whisk in the sweetened condensed milk, chocolate syrup and egg yolks.

Cook on low heat, whisking constantly, until the custard turns thick and creamy, about 5 to 7 minutes. Remove it from the heat and immediately whisk in the butter, vanilla, espresso powder, nutmeg and the remaining 2 tablespoons whisky. The custard will become smooth and glossy. Transfer it to a bowl through a fine sieve to remove any lumps. Place a piece of plastic wrap directly on top of the custard to prevent a skin from forming, let it come to room temperature and then chill it for several hours.

Once the custard is fully chilled, add the cream to the chilled* bowl of a stand mixer fitted with the whisk attachment (or use a large bowl and a hand mixer). Beat on low speed until cream turns foamy, then add the confectioners’ sugar and whip on medium-high until stiff peaks form, 2 to 5 minutes.

To assemble the Parfaits, stir the chilled custard to loosen it, then spoon or pipe a layer of custard about a third of the way up a clear jar or pretty wine or cocktail glass. Add a layer of crushed cookies and a layer of cream. Repeat with another layer of custard, cookies, and cream, finishing with a few crumbled cookies. Serve the parfaits immediately, or refrigerate for up to an hour (cookies will begin to soften after about an hour).