title_body: Baileys chocolate mousse - an alternative liqueur
upvoted_answer: I'm not a massive fan of Bailey's myself, but do love a chocolate mousse. Since unless you're going way overboard with the alcohol, you're not really going to disrupt the mousse and make it soupy, you can use anything that you think goes with chocolate. Personally, I love the following paired with a good dark chocolate:
  
  
  Kahlua/Tia Maria (most similar in spirit to Bailey's)
  Port or madeira
  Deep but not too peaty Scotch 
  Dark rum (I'd leave the continental "rums" to fruit desserts, where they excel)
  Brandy
  Kirsch
  
  
  I'd avoid lighter or delicate / floral spirits, since they don't really work (for me) with a deep dark chocolate.
  
  I'd keep it to under about a shot per cup to avoid thinning the mousse too much. And please try a tiny pinch of salt, which the original recipe is missing but is essential for a good chocolate dessert!