I've found where the Chida talks (in Chayim Shaal 1:74:6 and in Birkei Yosef, Yoreh De'ah 113:7) about "roasted peas" (אפונים קלויים; in Birkei Yosef he calls them קודאמאס) "that come from Tunis to Livorno," as to whether Bishul Akum applies to them. (The uncertainty is because in Tunis they are an important food, fit to be eaten by the nobility, "while here [in Livorno] they wouldn't even be served at a commoner's table.")
A few pages earlier in Birkei Yosef (Yoreh De'ah 112:9) he cites Maharit Tzahalon as permitting these peas, and also biscuits (that's probably the part that Shalom is referring to in his note on the original question), on the grounds that you don't know the manufacturer personally (i.e., he's like a פלטר), and that these foods are not socially significant enough for there to be a problem of חתנות. The first half of that argument is probably what R' Schachter is referencing. (Although לעניות דעתי it doesn't seem to be exactly the same: since Maharitatz calls him a פלטר, he'd presumably hold the same even if the manufacturer is in your town, as long as he sells to the general public rather than cooking the stuff especially for you.)
In any case, Chida himself argues against this position. He holds that the peas are prohibited (because the heter of פלטר doesn't apply to them), and that the biscuits indeed may not be eaten by people who are careful about פת פלטר.