Mix orange marmalade with Grand Marnier. Split the layers of the cake, making four. Spread each of the first three with a third of the marmalade mixture, then with 2/3 cup caramel crème fraîche. Frost outside of cake with remaining caramel crème fraîche. Chill cake, covered with a large inverted bowl to protect frosting, at least 1 hour and up to 1 day.