ounces unsweetened chocolate, chopped
egg yolks, lightly beaten
teaspoons vanilla extract
pastry shell (9 inches), baked
In a large saucepan, combine the sugar, cornstarch and salt. Stir in milk and chocolate. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer. Remove from the heat. Stir a small amount of hot filling into egg yolks; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir 2 minutes longer. Remove from the heat. Gently stir in butter and vanilla. Spoon into pastry shell. Cool on a wire rack. Cover and chill for at least 3 hours.