Prepare chocolate Crust: In heavy 1 litre saucepan over low heat or microwave-safe bowl in microwave oven, melt chcolate and butter; stir in chocolate crumbs until well mixed. Press crumb mixture firmly into bottom and side of greased 23 cm pie plate, making a raised edge around rim of plate. Freeze crust 10 minutes.
Meanwhile, prepare topping: In heavy 1 litre saucepan over low heat or microwave safe bowl in microwave oven, heat cream, chocolate, and corn syrup until cocolate melts, stirring until smooth. Stir in vanilla and set aside to cool to room temperature.
Prepare filling: Soften vanilla frozen yogurt at room temperature 15 minutes. With small ice-cream scoop, scoop about quarter pint vanilla frozen yogurt into 5 balls and place on plate. Place balls in freezer to harden.
Scoop remaining vanilla frozen yogurt in small dollops into chocolate crust; spread to an even layer. Sprinkle with 2 tablespoons chocolate crumbs; freeze pie 15 minutes.
Meanwhile, soften chocolate sorbet at room temperature for 15 minutes. Remove pie from freezer. Scoop about half pint chocolate sorbet in small dollops over vanilla layer in pie, spreading evenly. Sprinkle with 2 tablespoons crumbs. Scoop remaining 1.5 pints chocolate sorbet into balls around top edge of pie. Place vanilla frozen yogurt balls in center of pie. Cover pie with plastic wrap and freeze 15 minutes.
Drizzle 2 or 3 tablespoons cooled topping over pie and sprinkle with remaining 1 tablespoon crumbs. Cover pie loosely with plactic wrap and freeze until firm, 4 hours or overnight. Cover and refrigerate remaining topping.
To serve, let pie stand 15 minutes for easier cutting. Meanwhile, microwave remaining topping or reheat in small saucepan just until spoonable. Cut pie into wedges and serve with remaining topping.
Nutrition information: protein: 2 grams; fat: 15 grams; carbohydrates: 53 grams; Fiber: 4 grams; sodium: 258 milligrams; cholesterol: 35 milligrams; calories: 357.