Follow recipe or package instructions to bake single empty pie crust, pricking with a fork, and using a foil insert filled with beans or rice to keep the crust from separating from the pan. Set aside.

Preheat oven to 400 degrees and move oven rack to center location.

For filling:

Mix together sugar, cornstarch, salt and cocoa. Gradually add milk and oil, mixing well. Cook 4 minutes on high, stir. Cook 4 minutes more or until thick, stirring at the end of each minute. Separate yolks from whites, reserving whites for meringue. Beat egg yolks slightly. Gradually temper the egg yolks by adding 1 cup of hot mixture to the yolks very slowly, stirring constantly (this helps avoid "scrambling" the eggs with the hot milk mixture). Return tempered yolk mixture to first mixture, stir well. Cook 1 to 1-1/2 minutes, until thick, stirring every 30 seconds. Add vanilla and margarine; mix well. Pour into baked pie shell.

For meringue:

In a clean and dry bowl, beat egg whites (four reserved from filling plus two additional whites) with cream of tartar until foamy. Beat in sugar 1 tablespoon at a time; continue beating until stiff and glossy - meringue should be able to hold a firm peak. Beat in vanilla.

Spoon meringue on top of warm filling, making sure that it completely seals to the crust all the way around. Bake at 400 degrees for 10 minutes until golden brown. Let cool completely before serving, and keep any leftovers refrigerated..

Notes: This is my attempt to duplicate the wonderful chocolate meringue pie of my childhood from Otto's Cafe in Brenham. Otto's was a blue plate special kind of place with little ladies in hairnets staffing the counter - the pies were a mile high and so good. My parents' business, Washington County Electric, was just down the street, so we would run down there in the afternoon for a pie break when I worked there over the summers. The filling by itself is delicious and can be served as pudding with whipped cream. I use a 9-1/2 inch deep-dish pie pan for this and it's pretty full.