6 ounces unsweetened chocolate
2 tablespoons butter
2 cups granulated sugar
1/3 cup light corn syrup
2 cups half-and-half, divided
4 eggs
2 teaspoons vanilla extract
2 cups whipping cream

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 extract, whipping cream and remaining half-and-half. Freeze in ice cream maker according to manufacturer's directions.

Yields 1 1/2 quarts.