Preheat oven to 350°F (180°C). Spray one Torte Pan with nonstick cooking spray. Place an 8-in. (20-cm) circle of Parchment Paper over center of pan. In Classic Batter Bowl, combine cake mix, sour cream, sherbet and egg; whisk 1 minute or until smooth. Pour batter into prepared pan, spreading to edges. Bake 12-15 minutes or until center feels firm to the touch. Remove pan from oven to Stackable Cooling Rack; let stand 10 minutes. Invert cake onto Cake Pedestal; remove parchment and cool completely.
Meanwhile, zest orange using Microplane® Adjustable Grater to measure 1 tbsp (15 mL). Combine cream cheese, powdered sugar, sherbet and zest in Stainless (2-qt./2-L) Mixing Bowl; whisk until smooth. Reserve 3/4 cup (175 mL) of the whipped topping for garnish. Fold remaining whipped topping into cream cheese mixture.
Spread filling into well of cake. Refrigerate 1 hour or until ready to serve. Garnish with reserved whipped topping and mandarin orange segments just before serving.