Chocolate Pudding & Filling

1/3 cup all-purpose flour or 3 tablespoons cornstarch
1/4 teaspoon salt
1 cup granulated sugar
2 1-ounce squares baking chocolate, grated
2 cups whole milk
3 beaten egg yolks
2 tablespoons butter
1 teaspoon vanilla extract

In heavy saucepan whisk together the flour, salt, sugar and milk.  Stir in grated chocolate. Place over medium heat and cook until bubbly, stirring constantly.  Cook, stirring, for 2 minutes.  Remove from heat and stir some of the mixture into egg yolks, beaten well.  Return this mixture to saucepan, return to heat and cook another 2 minutes, stirring constantly, or until mixture thickens.  Remove from heat; stir in butter and vanilla.  Makes enough to fill a 9-inch pie shell.