It consists of layers of soft sponge and cream mousse finished with some garnishing depending on what the box says.
The first gateau bar I tried was some ASDA which got me hooked so I ended up trying the caramel biscuit one from TESCOs which is essentially the same and highly likely from the same manufacturer but made to TESCOs requirements.
Again, you have the same structure, eg the sponge layers and cream mousse.
At Tescos there was caramel biscuit and strawberry so I tried both.
I felt that the caramel biscuit was a bit plain but Biscoff lovers will love this because of the cinnamon as the caramel wasn't really strong enough for.
The Strawberry Gateau Bar however was amazing, the strawberry and cream mousse was just a match made in heaven.