A perfect Manhattan with bittersweet liqueur rather than aromatic bitters and a balancing dash of sweet maraschino liqueur.
If you can't obtain Picon...
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).