Step 1

Heat milk until it just begins to bubble around the edges in a 3-quart saucepan over medium heat (do not boil). Remove from heat, and whisk in chocolate morsels until melted. Cool slightly.

Step 2

Stir together cold water and cornstarch until dissolved.

Step 3

Whisk cornstarch mixture, sweetened condensed milk, eggs, and vanilla into chocolate mixture. Bring to a boil over medium heat, whisking constantly. Boil 1 minute or until mixture thickens and is smooth. (Do not overcook.)

Step 4

Remove from heat, and whisk in butter. Spoon mixture into piecrust. Cover and chill at least 8 hours.

Step 5

Beat whipping cream at high speed with an electric mixer until foamy; gradually add sugar, beating until soft peaks form. Spread whipped cream evenly over pie filling, and sprinkle with pecans and candy bar pieces.