Just lowered my rating by half a mark, as I found it too sweet. All the right ingredients, just the wrong proportions - investigation required.

I had made the Argentina sometime ago and enjoyed it. As it happens, I came across the following recipe in the "Tratado practico de coctelaria pasteleira y affines" bar guide by Mario Kardahi, Buenos Aires, 1966. (A very interesting book full of drink and food recipes, etc.). Portions adjusted to keep the original ratios.

Mar de Plata (page 85):
1 oz dry gin
3/4 oz dry vermouth
1/4 oz Benedictine
2 "blows" Grand Marnier (probably a few dashes or less than 1/6 oz)
lemon juice (qty not specified)

This wet martini variant is very tasty.

Another day another Argentina, or so I thought. Not concentrating, I added a whole shot of Cointreau instead of 1/4. I pressed on, not adding the Benedictine but continuing with both bitters. Actually not bad. Sweet, yes. In fact rather like an orange flavoured old fashioned boiled lolly. Have I invented something?!

Had all the ingredients sitting there waiting to be used! Quite delicious - gently spicy and slightly sweet. I probably wouldn’t have too many for just that reason, but one or two are a delicious change.

Good beyond belief. And I am not a Gin enthusiast. Don't be shy with the Angostura, especially the normal one. I propose to the bored drinker to go for two drops rather than one... (of normal angostura, not of the orange bitter)...but only after you have gone for the standard described here, which, knowing the overall low ability of my discerning skills, should be surely the one to look for at first. But really both the taste of Gin and the one of normal angostura have never blended so well.

Looking to use some Benedictine in a gin-based cocktail, I found this on Difford’s. We had to substitute a different bianco vermouth but a delicious result.