We are beginning Klal 58, which discusses mistakes made when reciting brachos.
The first point the Chayei Adam makes is that if one recites mezonos on bread, they are yotzei. The Nishmas Adam explains that the source for this halacha is pas haba’ah bekisnin. We have learned (shiur 1065, 1067), that there are three possible understandings brought in halacha regarding what makes something pas haba’ah bekisnin:
If it is hard and crunchy instead of soft and pliable
If other ingredients are added to the dough that significantly change its taste
If it is used as a shell to hold a filling
Each opinion is exclusive of the other opinions, in that each opinion holds that the other understandings are full-fledged bread. Nonetheless, we make a mezonos out of safeik even when only of these opinions is fulfilled. One could argue that a person in such a situation should be paralyzed, because they cannot make hamotzi (according to the opinion/s that the item is pas haba’ah bekisnin) and cannot make mezonos (according to the opinion/s that the item is hamotzi). The only way one could be yotzei when making a mezonos in such a case is if we hold that really, one is yotzei bedieved when they make a mezonos on bread.
If a person makes hamotzi on a mezonos item, the Chayei Adam differentiates between a cooked item (such as oatmeal, pasta, etc.) and a pas haba’ah bekisnin.
Regarding a cooked item, the Chayei Adam writes that one is not yotzei even bedieved, because it is a complete sheker (falsehood). However, on pas haba’ah bekisnin, one is yotzei bedieved, because we have learned (shiur 1065) that pas haba’ah bekisnin is inherently bread, but it “downgraded” due to its nature (i.e., the three understandings brought above). However, since it is inherently bread, if one were to make a hamotzi on it, they are yotzei bedieved.
The Mishnah Berurah does not discuss this question, so we can assume he concurs with the Chayei Adam.
If one made a mezonos on bread, they are yotzei bedieved.
If one made a hamotzi on mezonos, if the item is pas haba’ah bekisnin, they are yotzei bedieved. If the item is a cooked item (oatmeal, pasta, etc.), they are not yoztei even bedieved.