First make the custard. Combine the egg yolks and sugar in a mixing bowl. Stir in the cornstarch and mix to a smooth paste, then whisk in the milk.
Heat the cream in a heavy saucepan until just starting to simmer but not boiling. Gradually whisk the hot cream into the egg mixture, then return the mixture to the pan. Whisk continuously over medium heat for about 5 minutes, until thickened. Immediately pour into a pitcher and stir in the vanilla extract. Cover with plastic wrap to prevent a skin from forming and let stand to cool completely.
Thickly spread half of the ladyfingers with raspberry jam. Place the remaining ladyfingers on top to make a sandwich. If using sponge cake, slice horizontally into two or three layers and spread with jam. Arrange in a single layer in the bottom of a deep serving dish. Sprinkle with the crushed macaroons and the lemon zest.
Combine the whiskey and sherry and pour over the ladyfinger mixture. Let soak for 1 hour.
Spoon the cooled custard over the ladyfinger mixture.
Whip the cream with the sugar until stiff peaks form. Spread over the custard, leveling with a spatula. Cover with plastic wrap and chill for 1 hour, or until ready to serve.
Arrange the raspberries on top and decorate with candied violets or miniature macaroons.
Excerpted with permission from <a href="http://www.amazon.com/gp/product/1445473968/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1445473968&linkCode=as2&tag=craftfocom-20">"The Irish Pub,"</a> published by Parragon Books.