By HaRav Shimon Anshin shlit”a
With regards to a piece of bread that has been cooked, the Bracha depends on the size of the piece. If the size is that of a kazayis or more, it is still considered bread and the Bracha is Hamotzi.
However, if the size is less than a kazayis, it is not considered bread and the Bracha is borei minei mezonos with the after Bracha being al hamichiya. And this rule applies even if one were to make a keviyas seuda on it.
A. Cooking pieces together (in water).
i. If each piece is a kazayis or more, the blessing is Hamotzi.
ii. If only one piece is a kazayis and the other pieces less, should one intend to eat all of them, one makes Hamotzi on the large piece, however should one only intend to eat the small pieces, one makes borei minei mezonos.
iii. If all the pieces are less than a kazayis and when cooking them, they stick together as a single entity measuring more that a kazayis, the bracha is still borei minei mezonos.
B. Frying pieces together in oil.
i. If one deep-fries, it is considered “cooking” as if in water and the bracha follows the laws of B) above.
ii. If one fries in very little oil (only enough to prevent it from burning) it is considered “baked” (in an oven) and the bracha is Hamotzi.
iii. If one fries in an average amount of oil, there is a difference of opinion between the poskim, most holding that it is considered to be “cooked” in water. [Because of the uncertainty], the Mishna Berura holds that it is correct that one should only eat it within the context of a Seuda.
C. “Matzah Brai” – Broken pieces of Matzah mixed with eggs and fried in oil.
i. If each piece is the size of a kazayis or more, the bracha is Hamotzi and we make Birkas hamazon afterwards.
ii. If the pieces are crushed and less than the size of a kazayis and fried in deep oil, even should they become amassed into a single entity, we make borei minei mezonos and al hamichiya afterwards.
iii. If the pieces are crushed and less than the size of a kazayis respectively, but fried in a in very little oil (only enough to prevent it from burning) one should eat it in the context of a seuda (because of the differences of opinion as to which bracha to say).
iv. If the pieces are crushed and less than the size of a kazayis respectively, and are fried in an average amount of oil, it is preferable to eat it only in the context of the seuda (because of the differences of opinion as to what the bracha to say), however should it be difficult or inopportune to eat it in the context of a seuda, as is often the case with younger children, one should make borei minei mezonos and al hamichiya afterwards. One should not make a stringency and make hamotzi with birkas hamazon afterward, and would be considered a bracha in vein (levatala) according to most opinions. (At the very least making borei minei mezonos would retrospectively (bediyeved) cover even regular bread)
Note: All references to the being “in context of a seuda” is when someone is hungry, makes Hamotzi on Matzah and eats the “Matza Brai” which is then covered by the Hamotzi. In such a case it is enough that one only makes Hamotzi on a kazayis of Matzah. However, should one only wish to snack on the “Matzah Brai” and therefore makes Hamotzi on a kazayis of Matzah only in order to “cover oneself” in order to get over a potential doubt as to which bracha to make, it is not clear according to the poskim as to whether this approach is in fact correct or not, and therefore, it would be better to make a borei minei mezonos on the “Matzai Brai” alone.