We rarely have Creme de Menthe in the house and so substituted Italicus Rosolio di Bergamotto, which worked nicely for us. (Acqua Bianca might also work but we didn't have a bottle of that to hand either.) Perhaps without the Creme de Menthe the colour is more subdued. Anyway, a deliciously kitsch party drink.
I used french white crème de cacao (flavour is something in between dutch white and dark) So I'm not sure if this will fit as well with dutch, but doubling the amount of Curaçao did wonders!