There’s a bakery in Newport Beach named C’est Si Bon, and they have the most heavenly cake I’ve had the pleasure of eating in the past 15 years or so (the only other who measures up is from a bakery in Karachi).
If you have the chance to be in Orange County, go there and buy the chocolate mousse cake, which comes both as a slice and a whole sheet fit for about 20 people.
You won’t regret it, I swear.