Q. Does one recite Hamotzi on fake bread? If he did so by mistake, does he need to say another Bracha?
A. On question 3161 we mentioned regarding bread made from special types of flour that Horav Shlomo Miller's and Horav Aharon Miller's Shlit'a opinion is that even a mixture where the wheat is only around 18% approximately (kedei Achilas Prass), would require Hamotzi. Horav Shlomo Miller’s Shlit’a opinion is similar. However, he recommends on the onset having mostly wheat, yet abstained from mentioning percentages, since there are other factors involved, that would render exact numbers problematic.
Obviously bread that does not contain any amount of the five types of grain required for being considered bread, will not qualify for that blessing.
Although after the fact the blessing of Mezonos will exempt other foods including the ones we recite shehakol on them, Horav Shlomo Miller's Shlit'a opinion is that Hamotzi is different since we mention the word 'Lechem' and that refers to real bread, so fake bread does not qualify.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a