It always amazes me how so many Argentines know, and agree, that the best medialunas in Argentina are the ones at Atalaya in Chascomús. One only needs to mention the name of the town “Chascomús” and they will reply “the best medialunas!”. And they are right. Of course, one should not expect the same taste their French brothers and sisters, but then they are not called “croissants”, but “medialunas”. They are sweeter and softer then the French ones. Where as the croissant is (in my opinion) best with a bit of (real) butter on it, a medialuna (especially the ones at Atalaya) don’t ask for anything. They are perfect the way they are. Although I certainly can’t resist one with ham and cheese in them.
The turnover at Atalaya is so big, that the medialunas always come straight out of the oven and are still warm. At the beginning and the end of an extended weekend, or during holidays, there are huge lines, as everyone driving to the coast does not want to pass this place without buying some.
That is what you should do. If you don’t feel like driving 100km south just to buy these delicacies, make sure you stop by whenever you drive to the coast. The biggest one is at km 113 on ruta 2, there is another one by the lake at Chascomús and one in Mar del Plata. Also try the palmeras (I prefer them heated up a bit in the oven), and the empanadas. Don’t let the big crowds scare you off, the service is quick, and they are worth it!
If medialunas are not quite your taste, and you prefer the croissants, I still think the best ones are found here.