A perfect Manhattan with bittersweet liqueur rather than aromatic bitters and a balancing dash of sweet maraschino liqueur.
If you can't obtain Picon...
If French amaro refers to Picon Amer, then it should be said that Picon actually comes from Belgium. However, it's so good that it could be French ! ;)
Although I tend to prefer the dryer Brooklyn Cocktail, I must admit that this version is... perfect ! One of my favorite cocktails in winter. It's so comforting.
Picon Amer is obviously produced in Belgium nowadays, but I think it’s safe to say that it is an original French bitter, given that Gaétan Picon was French, born and bred, although he first started producing the beverage in Algeria. See for instance https://en.wikipedia.org/wiki/Picon_(apéritif).
Although I tend to prefer the dryer Brooklyn Cocktail, I must admit that this version is... perfect ! One of my favorite cocktails in winter. It's so comforting.