Preheat oven to 360*F

In saucepan, whisk 2 cups sugar, cocoa powder, and flour. Whisk in evaporated milk and vanilla. Beat egg yolks, and stir into pan. Add butter or margarine. Heat, stirring constantly just until butter is melted. Pour filling into unbaked crust.

Bake in preheated oven for 35 to 40 minutes or until pie is not “wobbly” when shaken.

Beat egg whites in clean glass or stainless steel chilled bowl, until soft peaks form. Gradually add 1/4 cup sugar, beating constantly, until stiff peaks form. Spread meringue on pie.

Return to oven and bake until meringue is golden brown.

Cool, refrigerate until ready to serve.