I love the Old-Fashioned Chocolate Cake (Feast, p269), but was wondering would it be dense enough to take a fondant covering along with a few fondant decorations? Absolutely love Nigella's recipes! Thank you so much.
Most sponge cakes, including the Old Fashioned Chocolate Cake, are able to take the weight of one layer of rolled fondant (ready to roll) icing. The main problem you are likely to come across is that if the surface of the cake is not completely smooth then you will see some lumps and bumps underneath the icing. This can be mitigated by carefully trimming the cake with a serrated knife, using a fairly thick layer of fondant icing, using a layer of marzipan below the fondant layer or by using a layer of buttercream or chocolate ganache underneath the fondant.
Many professional decorators like to use a thin layer of buttercream as it helps to fill in any indentations and is pleasant to eat. Smooth the buttercream with a palette knife (icing spatula) before adding the fondant layer. Try not to let the buttercream set as it will stop the fondant from sticking so well and don't use a buttercream that needs refrigeration (usually one made with eggs) as the fondant will "sweat" if it is kept in the fridge. The cake should be able to support most fondant based decorations, as long as they are not very large.