Thanks Simon for directing my attention to this Chartreuse replacement. Up to now it is the only one which really works in cocktails, although, as Frederic notes, by drinking it neat it is different. The lower price and ABV should it make interesting for professionals.

I used this as the sweet component of the martini variant that Simon calls the adjournment. In honor of the political situation in America today, I am calling this theCloosterfuck martini.
Whatever the political situation, it is delicious.

Although it is less complex and less abv, it is a very good and cheap alternative for Green Chartreuse. With the low price (€14) point in the Netherlands, this is a very nice sub allowing me to make crushable GC cocktails like the Pina Verde without guilt.

Boomsma is sweeter and less complex than Chartreuse Verte. It is also considerably cheaper, not to mention easier to find. It won't replace the real thing for a neat sipper, but in mixed drinks it is a very good substitute, especially with a few dashes of Elexir Vegetal as mentioned above. I've made a few drinks that way with differences ranging from imperceptible to minimal.