Mix sugar, flour, salt, and cocoa in top of double boiler.

Stir in milk and cook for 15 minutes over hot water, stirring constantly until thick.

Add egg yolks and cook 3 minutes.

Add butter, cool.

Add vanilla and pour into baked 9" pie shell.

Make meringue from remaining 3 egg whites, using 6 tablespoons sugar and 1 tablespoon lemon juice or 3/4 teaspoon cream of tartar.

Spread on pie and bake at 350 degrees for about 15 to 20 minutes.