If one is makpid on pas yisroel does that mean they have to be makpid on pas haba bkisnin, such as pretzels or cookies?
The prohibition does extend to cookies, pastries, and so on. However, If the batter from which the cookies are prepared is liquidy, and does not resemble a bread-dough, some maintain that the the prohibition would not apply.
See Tosafos, Beitzah 16b; Rema, Yoreh De’ah 112:6; Biur Ha-Gra, loc. cit. 4; Chochmas Adam 65:7; concerning a liquidy batter, see Shach, Yoreh De’ah 112:18; Chelkas Binyanim 112:64 cites authorities who dispute the leniency of Shach, and rule that all forms of pas haba bekisnin fall under the prohibition of pas akum.