The list is here (sorry it's in French). They don't mention the famous 'chocolat chaud à l'ancienne' at Les Deux Magots but they should. Frankly I don't see the point of going to Les Deux Magots and order anything else. À l'ancienne means old-fashioned. They're not diluting powder into water, this is not starbuck. It's had cooked for a long time and is thick with a balanced flavor you didn't think chocolate was capable of. But it's not too sweet, just bitter enough, complex, decadent but not to the point of indecency. Like velvet on the tongue (chocolate-flavored velvet).
image credit here.