In a saucepan, combine egg yolks, milk, sugar, lemon zest and salt until blended. Cook over medium-low heat until mixture reaches 160°, about 12-15 minutes. Remove from the heat; stir in vanilla. Cover and refrigerate for 1 hour.
Meanwhile, combine mincemeat and lemon juice. Tear cake into 1-in. cubes; place a third of the cake in a trifle bowl or 2-qt. serving bowl. Top with a third of the custard and half of the mincemeat. Repeat layers. Top with remaining custard.
In a bowl, beat cream and confectioners' sugar until soft peaks form; spread over custard. Garnish with cherries if desired. Cover and chill for at least 2 hours.