sugar, cornstarch and salt in a saucepan.
Gradually stir in milk. Cook over medium heat
until mixture begins to simmer, stirring constantly.
Gradually stir about 1 cup of the hot mixture
into the beaten eggs. Add to remaining hot
mixture, stirring constantly. Cook and stir
over low heat until slightly thickened (about
2 minutes). Stir in melted chocolate. Beat
with a whisk until mixture is smooth. Stir
in half and half, whipping cream and vanilla.
Cover and refrigerate 2 hours. Freeze as directed.