Combine sugars, cornstarch, gelatin, salt and milk in a saucepan over medium-low heat, constantly whisking to combine. Add in chocolate and allow to come to a boil. Boil for one minute and remove from heat. Add vanilla.

Beat egg yolks together and slowly pour one cup of the pudding mixture into the egg yolks while constantly whisking to prevent eggs from cooking. Pour egg yolk mixture back into the saucepan and mix all together. Pour into the pre-baked pie crust.

To make the meringue, add egg whites, sugar and cream of tartar and beat all three ingredients together until still and able to form peaks.

Spread meringue over the top of the pie to the edge of the crust, sealing the pie.

Bake in preheated 350-degree oven for 15 minutes.

Chill prior to serving.