Is one allowed to wash and bentch on “Mezonos” bread?
Due to the issues involved with Mezonos bread, I try not to eat it. However, at times, it is the only available option. I would prefer to wash and Bentch. Lechatchila, may one make Hamotzi on bread that is 2/3 Mei Peiros?
If one eats the right amount – the volume of four eggs, and is satiated, they wash and say Hamotzi on any baked cake or bread.
The same applies if they eat the volume of 21 eggs even if they are not satisfied.
See also Halacha2go.com #54.
סדר ברכת הנהנין ב, ב.