Orange Creamsicle Cake

Invert cake onto serving plate. Fill center hole with sherbet, packing in. Cover with plastic wrap and freeze at least 4 hours or overnight. (Once the cake is frozen, it can be wrapped and stored in freezer up to 2 weeks.) To serve: Unwrap; transfer frozen cake to a serving plate. Frost sides and top with thawed whipped topping or whipped cream. Sprinkle candied orange peel on top, if using. Using a citrus zester, remove the peel from 1 orange in strips. Or use a vegetable peeler to remove the peel from the orange in vertical strips, avoiding as much of the white pith as possible; cut into smaller strips. Bring 2 cups cold water and the peel to a boil in a 2-qt saucepan; drain. In the same saucepan, whisk 1 cup water with 2 cups sugar until sugar dissolves. Add the peel and bring to a boil over medium heat. Reduce heat; simmer the peel 10 to 15 minutes until tender and translucent. Drain; let cool.