Preheat oven to 350 F. Place 2 cups of the pecans in food processor; cover. Process until finely ground, using pulsing action. Mix with granulated sugar and butter; press into 9-inch pie plate. Bake 12 minutes or until lightly browned. Cool completely. (If crust puffs up during baking, gently press down with back of spoon.) Microwave caramels and 1/3 cup of the whipping cream in microwavable bowl on high 3 minutes or until caramels are melted, stirring after each minute. Pour into crust. Chop remaining 1 cup pecans; sprinkle over pie. Place chocolate, remaining whipping cream, powdered sugar and vanilla in saucepan; cook and stir on low heat just until chocolate is melted. Pour over pie; gently spread to cover top of pie. Refrigerate at least 2 hours.