This post is part of my personal challenge to bake my way through all the challenges of the Great British Bake Off. The challenge below is the signature challenge for week seven (patisserie week) of series two: a layered mousse cake.
Think a crisp, rice-cereal-marshmallow-and-hazenut base, bound together with melted chocolate. Think a silken, rich yet feather-light mousse that melts in the mouth like snow, leaving behind the impression of chocolate and hazelnut. Think a soft, buttery cake which adds another layer of contrast to the delicate mousse and robust, crunchy base. That is this cake and it is absolutely stunning, and completely worth it.
Lest you think the above is sheer hyperbolic food porn, I assure you that everyone I served this to thought it was utterly divine. It’s a special cake, rather than an everyday, cut-and-come-again cake, that would be perfectly well-suited to being served as a dessert at the end of a lovely dinner party (perhaps served with some of the Frangelico that lends it its hazelnutty, smoky flavour).
The baking ladies of series two of GBBO (who were tasked to make mousse cakes) almost all used gelatine in their mousse, but this one relies on just the cream for aeration and lift. This is of course what gives the mousse its delicate, melting quality, but also means that it isn’t as structurally strong as one reinforced with gelatine, hence lengthy chilling is essential. The mousse is prone to melting, as well, because of the soft texture and structure, so chill it between serving.
The recipe I used is adapted from a Bon Appetit recipe which I found on Epicurious. Apart from a few additions and adaptations based on the reviews (for example I added marshmallows to the base because a lot of the reviews said the base was too hard) and adapting it for ingredients easily found in the UK, I have also tried to streamline some steps as it was quite a fussy and fiddly recipe, which required odd things such as baking the cake in a particular-sized tin and then trimming it to fit another size of tin. Just say no. I didn’t do it and I didn’t need to.
For the hazelnut flavour, this mousse cake relies on a good dose of Frangelico – hazelnut liqueur – in addition to the use of hazelnuts in the base. You can occasionally find hazelnut liqueur which is not Frangelico, but it’s not easy and the price is around the same. It’s definitely quite a niche product and I know how wearying it can be to be guided towards an ingredient which is expensive, sometimes difficult to find, and not very versatile. In my defence, though, this cake is really delicious and very special. If you want to try it but are desperate not to buy in the Frangelico, dark rum could work.