In a large, heavy saucepan, melt chocolate and butter over low heat, stirring often. Stir in sugar, corn syrup and 2/3 cup of the half and half. Stir over medium-low heat until mixture comes to a boil. Simmer 4 minutes without stirring; set aside.

In a small bowl, beat eggs until blended. Stir in 1/2 cup of hot chocolate mixture. Stir egg mixture into remaining chocolate mixture. Cook and stir over medium heat until slightly thickened, about 1 minute.

Cool to lukewarm. Stir in vanilla, whipping cream and the rest of the half and half. Freeze in ice-cream maker according to manufacturer's directions.

[From: Chocolate Mousse and Other Fabulous Chocolate Creations, p. 137, by Betty Malisow Potter. New Boundary Designs, Chanhassen Mn, 1986.]

[Notes: A double batch is too big for a 3-quart saucepan. It also won't fit in my "4 Quart" ice cream maker.]