A. For the reader, here’s a little background. In addition to the mainstream Kosher symbols like OU, OK, Star-K, Chaf-K and so on, there are additional standards and stringencies (all with solid basis in Jewish Law) that some communities keep. For example the issue at hand here: Pas-Yisrael. This goes back to Talmudic texts, in addition to all Kosher ingredients and equipment, Pas Yisrael dictates that an observant Jew be involved in some degree with the baking. The Talmud offers a leniency in time of need, which is why the OU, OK, etc certify baked goods that do not have this stringency. But some communities, including Chabad, still stick with the original Talmudic ruling. So we won’t eat mainstream baked breads or pastries sold in regular grocery stores, unless we know that Pas Yisrael has been arranged for.

So that’s the Pas-Yisrael background. Now, Graham-Cracker crusts present an interesting question, even for those who are observant of Pas Yisrael. They are non-Pas-Yisrael graham-crackers smooshed and crushed (and baked) into a crust. That crust is possible to eat as-is, without further baking, such as in an ice-cream pie. Or it can be baked again at home, and its taste improved by baking into a dish. Does the re-bake at home add that desired level of Pas-Yisrael for those who keep this stringency?

Basically, because these crusts are ready to eat as is when purchased, further baking at home doesn’t add the Pas Yisrael level that is desired. Which is why we only purchase Pas-Yisrael graham cracker crusts, such as those produced by Jewish companies.

There are some opinions who say that the re-bake at home improves the taste and therefore it can add that level of Pas Yisrael, especially in those products which specifically have baking instructions on the label that it intended to bake at home (even if edible without it).  This may not be the case with graham cracker crusts but may be true with other crusts or pre-made pastries.

BTW, most frozen pie crusts must be baked at home to be edible. So as long as they have a reliable Kosher symbol, once they are baked at home in a Kosher kitchen they get Pas-Yisrael status as well.