Prepare pie crust and cool according to the package directions.
In a small saucepan, combine 1 tablespoon of cornstarch, 2 tablespoons sugar, cocoa, and a dash of salt. Gradually whisk in 1/3 cup of milk, whisking until smooth. Cook for about 2 minutes over medium-low heat, stirring constantly.
Stir in the chocolate chips and bring to a boil over medium heat. Reduce heat to low and cook for 1 minute, stirring constantly, until thickened. Spread chocolate mixture into the bottom of the cooled crust.
Combine 2 tablespoons cornstarch, 1 cup of milk, 1/2 cup sugar, 1/4 teaspoon salt, eggs, and butter in a medium saucepan over medium heat. Whisking constantly, bring the mixture to a boil over medium heat. Reduce heat to low and cook for one minute, until thick. Remove from the heat and stir in the vanilla.
Beat the cream cheese with an electric mixer until smooth and light, about 30 seconds. Add 1/4 cup of the hot custard to the cream cheese and beat, just until blended. Stir the cream cheese mixture into the remaining hot custard.
Slice the bananas and arrange the slices from edge to edge over the chocolate layer. Spoon the custard over the bananas and smooth out to cover. Press plastic wrap onto the surface of the custard and chill the pie for 3-4 hours.
Remove the plastic wrap and spread the whipped topping over the custard. Garnish with chocolate curls or mini chocolate chips. Chill until ready to serve.