Method: Sift cocoa, sugar, and flour together. Separate eggs; set egg whites aside for meringue. Add egg yolks to milk and wisk until well blended. Add milk mixture to flour mixture a little at a time, wisking until well blended. Cook over medium heat, stirring constantly with rubber spatula, until thickened. Remove from heat; add vanilla and a lump of butter or margarine. Pour into prepared pie shell. Beat egg whites with 1/4 teaspoon cream of tartar until starting to firm up; add 4 tablespoons of sugar and beat until soft peaks form. Put on top of chocolate mixture in pie pan. Brown at 325 until meringue is nicely browned.