While you could use vanilla ice cream and orange cake, you may want to consider swapping out the ice cream for orange sherbet ...

Once the vanilla ice cream “wall” has firmed up in the pan, spoon the chocolate ice cream into the center of the cake pan ...

Serve the cake in slices with a scoop of ice cream and a drizzle of sauce. Make things easier for yourself by preparing the oranges a few days in advance and buying vanilla or clotted cream ice ...