Roll pastry on floured surface into circle 1 inch larger than inverted 9-inch pie plate. Ease pastry into plate; trim and flute edge. Pierce bottom and side of pastry with fork. Bake in preheated 375F oven 10 to 12 minutes or until crust is golden. Cool on wire rack.
Combine Equal®, cornstarch, cocoa and salt in medium saucepan. Stir in milk. Heat to boiling over medium-high heat, whisking constantly. Boil and stir until thickened, about 1 minute.
Beat eggs in small bowl; whisk about 1 cup chocolate mixture into eggs. Whisk egg mixture into chocolate mixture in saucepan. Cook over very low heat, whisking constantly, 30 to 60 seconds. Remove from heat. Stir in vanilla.
Spread hot filling in baked crust. Refrigerate until chilled and set, about 6 hours. Garnish top of pie with dollops of whipped topping and chocolate curls, if desired. Cut pie into wedges.