Prepare white chocolate custard recipe: In a large heavy saucepan, stir sugar, cornstarch and salt with a wire whisk until mixed together. Gradually stir in milk until smooth.
Cook over medium heat, stirring constantly, until mixture thickens and boils; reduce heat and cook for 1 minute. Remove saucepan from heat.
Gradually stir about half of the hot milk mixture into egg yolks. Slowly pour egg mixture back into milk mixture, stirring rapidly to prevent lumping. Cook, stirring constantly, until custard just begins to bubble. Remove from heat.
Stir in chocolate and vanilla until melted and smooth. To keep a skin from forming over the top, press plastic wrap directly onto the top of the hot custard. Cool to room temperature without stirring, then in refrigerator about 1 hour.
Prepare dessert as follows: Cut pound cake into small cubes.
In small bowl, with fork, stir together cranberry-raspberry sauce and liquor until smooth.
In a 3-quart clear glass bowl, place about half of the cake chunks.
Remove 2 tbsp cranberry-raspberry sauce; cover and set aside. Spoon about half of the remaining sauce mixture over cake, and top with about half of the white chocolate custard.
Repeat layers with remaining cake, sauce mixture, and custard. Cover and refrigerate at least 4 hours.
To serve, in small bowl, whip heavy cream, confectioner's sugar and vanilla just until stiff peaks form. Reserve about 1 cup whipped cream; spread remaining cream over trifle.
Spoon reserved cranberry sauce mixture into small decorating tube (or a small plastic bag with a small slit in corner) and pipe in a desired design on top of whipped cream. Draw a sharp knife tip across lines to feather the design.
Spoon reserved whipped cream into decorating bag with a star tip and pipe around edges of trifle. Garnish with nuts.