2-1/2 cups milk, divided
1 cup sugar
3 tablespoons all-purpose flour
5 tablespoons cornstarch
1/2 teaspoon salt
3 egg yolks
2-1/2 ounces unsweetened baking chocolate
2 tablespoons butter
1-1/2 teaspoons vanilla extract
1 pastry shell (9 inches), baked
In a 1-quart saucepan, heat 1 1/2 cups milk and sugar. In a mixing bowl, combine the flour, cornstarch and salt. Add egg yolks and remaining milk; mix well. Temper this mixture by adding a third of the hot milk mixture. Return all to the saucepan. Bring to a boil; boil and stir for 1 minute.
Remove from the heat. Add chocolate and stir until melted. Finish with butter and vanilla. Pour into pastry shell. Refrigerate until set.