In a large saucepan, combine the condensed milk and water.

Add the chocolate pudding mix (COOK AND SERVE, not instant).

Mix well to combine the pudding mix with the milk mixture.

Add the chopped unsweetened chocolate square.

Over medium heat, cook and stir rapidly until the chocolate melts and the mixture thickens.

Remove from heat and beat the mixture until smooth.

Cover the surface of the chocolate mixture with plastic wrap to prevent a skin from forming.

Chill the mixture thoroughly in the refrigerator.

Stir the chilled chocolate mixture again to ensure smoothness.

Gently fold in the stiffly whipped heavy cream.

Pour the chocolate cream filling into the pre-cooked pie shell.

Chill the pie for at least 4 hours, or until the filling is set.