Gemara

(Rav Yosef): Regarding Chavitza (a food made with bread crumbs):

If some of the pieces are at least a k'Zayis, one blesses ha'Motzi (and Birkas ha'Mazon);

If all the pieces are less than a k'Zayis, one blesses Borei Minei Mezonos (and me'Ein Shalosh).

Support (Rav Yosef, for himself - Beraisa): One blesses ha'Motzi on Menachos;

(Mishnah): Every Minchah is broken into pieces the size of olives.

Question (Abaye): Tana d'Vei R. Yishmael says that they are broken very finely, like flour. Surely, Kohanim would bless ha'Motzi!

Suggestion: Perhaps they do not bless ha'Motzi!

Rejection (Beraisa): If one gathered a k'Zayis (of crumbs), and ate it (on Pesach), if they are Matzah, he was Yotzei (they are considered "Lechem");

If they are Chametz, he is Chayav Kares.

Answer #1: The case is, he combined them into one mass.

Objection (Seifa): This is when he ate them within the time to eat half a loaf. (If he made them one mass, it should say that he ate it!)

Answer #2: The case is, (a k'Zayis of) the (original) loaf is still intact. (Since it retains its importance and its Berachah, its crumbs retain their Berachah.)

Question: What was the conclusion?

Answer (Rav Sheshes): One blesses ha'Motzi, even if all the pieces are less than a k'Zayis.

(Rava): This is only if they still look like bread.

Berachos 37a (Beraisa): If wheat was ground (into flour), baked and cooked, if the pieces are intact, one blesses ha'Motzi.

If the pieces are not intact, one blesses (Borei Minei) Mezonos.

38b Rav Nachman: Shmuel says that one blesses Borei Pri ha'Adamah on cooked vegetables. Ula said in the name of R. Yochanan that one blesses sheha'Kol;

Rav Nachman: They argue (like the following Tana'im):

(Beraisa - R. Meir): One is Yotzei eating Matzah with a wafer (even if it was) soaked (in water), or if it was cooked but did not dissolve;

R. Yosi says, one is Yotzei with a soaked wafer, but not if it was cooked, even if it did not dissolve. (Cooked bread is not called bread. Likewise, cooking changes the Berachah for food. R. Meir holds that cooking changes neither.)

Rejection: No. R. Yosi disqualifies cooked Matzah because it loses the taste of Matzah, but he agrees that vegetables do not lose their Berachah.

39a (R. Chiya bar Ashi): The Berachah on Tzenumah (dry bread soaked in a bowl) is ha'Motzi.

Rishonim

Rosh (Berachos 6:10): Rav Yosef says that one blesses ha'Motzi on Chavitza if some pieces are at least a k'Zayis. If all the pieces are less than a k'Zayis, one blesses Mezonos. Rav Sheshes says that one blesses ha'Motzi even if all the pieces are less than a k'Zayis. Rava said that this is only if they have the form of bread. This is the Halachah. Rashi says that Chavitza is bread cooked in a pan. This is difficult. If so, what was Rav Yosef's support from crumbs of a Minchah, which were not cooked? We can say that frying in oil is like cooking. However, what was the proof from one who gathered a k'Zayis of crumbs? They were not cooked or fried! Also, we should have challenged Rav Sheshes from the Beraisa (37a) that says that if the pieces are not intact, one blesses Mezonos! The Yerushalmi explains that 'intact' means at least a k'Zayis. R. Tam explains that Chavitza is bread crumbs stuck together through milk or honey. The Aruch explains that they are stuck together through soup. Anything that stuck together is called Chavitza, e.g. date-Chavitza. There are three cases. 1) If it was cooked, if the pieces are a k'Zayis, one blesses ha'Motzi. If they are not a k'Zayis, even though they appear to have the form of bread, one blesses only Mezonos. Since it was cooked, it is not considered the form of bread. 2) If it was not cooked, just it is stuck together through honey or soup, if the pieces are a k'Zayis, one blesses ha'Motzi even if it lacks the form of bread. If they are not a k'Zayis, if they have the form of bread, one blesses ha'Motzi, and if not, it is Mezonos. 3) If it is not cooked or connected, just it is crumbed finely, even though it does not have a k'Zayis or the form of bread, one blesses ha'Motzi. Since it is bread by itself, it never loses the law of bread. This is from R. Yonah. This is the Halachah. The Berachah on Tzenuma is ha'Motzi (39a). R. Chananel says that this is if it has the form of bread. Really, it need not have the form of bread. Since nothing else was mixed with it, it never loses the law of bread. One blesses ha'Motzi.

Mordechai (Berachos 119): Cooked bread has the form of bread if it appears like bread. It did not totally dissolve. It is recognized and known that it is bread. We hold like Rav Sheshes and Rava, that one blesses ha'Motzi on pieces less than a k'Zayis, since it has the form of bread, even if it was cooked, like Rashi explained. A Beraisa said that if the pieces are not intact, one blesses Mezonos. Rav Sheshes says that this is when they dissolved in a Keli Rishon, like Avi ha'Ezri distinguishes regarding Pas Tzenuma.

Tosfos (75b DH Liket): The Beraisa about gathering crumbs does not discuss Menachos. The Beraisa says 'if they are Chametz, he is Chayav Kares. Menachos are not Chametz!

Gra (OC 168:10 DH v'Im): Also, it cannot discuss Menachos, because Matzah must be permitted to eat "b'Chol Moshvoseichem" (anywhere).

Tosfos (37b DH Amar): The Halachah follows Rava, for he is Basra. It depends on having the form of bread. According to Rashi, this is even if it was cooked. The Yerushalmi says that the pieces must be a k'Zayis, for normally only then it has the form of bread, but sometimes it has the form of bread even if they are less than a k'Zayis. If bread crumbs were put in water and the water whitened, it lost the form of bread. R. David of Mitz did so in order to eat to strengthen himself to teach, without delaying for Birkas ha'Mazon.

Poskim

Shulchan Aruch (OC 168:13): Chavitza, i.e. bread crumbs stuck together through soup, if it was cooked, if the pieces are a k'Zayis, even though they do not have the form of bread, one blesses ha'Motzi . If they are not a k'Zayis, even though they appear to have the form of bread, one blesses only Mezonos.

Beis Yosef (DH Amar): This case is learned from the Yerushalmi. A Beraisa taught that if bread was cooked, one blesses ha'Motzi if the pieces are intact, and Mezonos if they are not. The Yerushalmi explains that 'intact' means at least a k'Zayis. It does not depend on the form of bread.

Beis Yosef (DH u'Piresh): The Mordechai (126) says that Pas Tzenuma is dry bread soaked in a bowl. Bahag says that this refers only to a Keli Sheni, i.e. hot water was poured on it. If it was in a pot, i.e. a Keli Rishon, even if it is intact, it lost the law of bread. Based on R. Yonah, we must say that Bahag discusses when the pieces are less than a k'Zayis. Therefore, in a Keli Rishon, even though it is intact (has the form of bread), it lost the law of bread. If the pieces are a k'Zayis, one blesses ha'Motzi even if it lacks the form of bread.

Magen Avraham (25): In (the Tur in) YD 68, some say that Iruy (pouring from a Keli Rishon) cooks. Therefore, if Iruy was done on bread crumbs, one should not eat it if it has the form of bread, and surely not to eat to satiation, for then it is a Safek mid'Oraisa about Birkas ha'Mazon. He should bless on other bread first.

Mishnah Berurah (49): If bread was cooked, if the pieces are at least a k'Zayis, it is still considered bread even if it lost the form of bread. If the pieces are not a k'Zayis, even if they have the form of bread one blesses Mezonos, for it is considered a Tavshil (cooked food).

Mishnah Berurah (50): When it was cooked, it does not matter whether the pieces stick together. The Shulchan Aruch mentions it due to the next case.

Mishnah Berurah (52): 'Cooked' is if it was in a Keli Rishon, or at least it was Yad Soledes Bo. A Keli Sheni does not cook; its law is like the next case in the Shulchan Aruch (unless the water whitened).

Kaf ha'Chayim (79): If it is not Yad Soledes Bo, even on the fire it is not considered cooking.

Mishnah Berurah (53): If even one piece is a k'Zayis, he blesses ha'Motzi on it, and exempts the other pieces.

Mishnah Berurah (54): The piece must be a k'Zayis before cooking, but not that it inflated through cooking or liquid or other pieces stuck to it.

Mishnah Berurah (56): If it was not cooked, rather, fried in liquid in a pan, the Magen Avraham (36) connotes that this is not cooking, and the form of bread helps, like the next case in the Shulchan Aruch. Other Acharonim disagree. If the pieces are less than a k'Zayis but have the form of bread, one should eat it only in a meal.

Mishnah Berurah (57): In all these cases that one blesses Mezonos, this is even if he fixed a meal on it and ate to satiation, for it is not bread at all. It is like a cooked food.

Kaf ha'Chayim (78): Eshel Avraham says that if the pieces were a k'Zayis when they were cooked, even if later they were crumbed, one blesses ha'Motzi. He concluded 'this requires investigation.'

Shulchan Aruch (ibid.): If it was not cooked, just it is stuck together through honey or soup, if the pieces are a k'Zayis, one blesses ha'Motzi even though it lacks the form of bread. If they are not a k'Zayis, if they have the form of bread, i.e. it is recognized and known that it is bread, one blesses ha'Motzi . If it lacks the form of bread, one blesses Mezonos

Beis Yosef (DH Amar): This is Rav Sheshes' law. Even if the pieces are less than a k'Zayis, one blesses ha'Motzi if it has the form of bread. Surely, if the pieces are a k'Zayis, one blesses ha'Motzi even if it lacks the form of bread, like Rav Yosef. Rav Sheshes comes to add to Rav Yosef cases in which we bless ha'Motzi, and not to detract. The form of bread means that it is recognized and known that it is bread.

Magen Avraham (24): It need not stick together through the soup. The same applies if it was soaked. The Chidush is even if they stuck together, if each piece is less than a k'Zayis, one blesses Mezonos.

Mishnah Berurah (59): Many Acharonim say that if Matzah balls were cooked in a pot or fried in a pan in liquid, this is like cooking, and one blesses Mezonos even though each ball is a k'Zayis. This is the custom. If one baked them, one should eat them only in a meal, but if there is much oil or honey, one blesses Mezonos. If one kneaded them only with water, it is proper bread.

Kaf ha'Chayim (85): If Matzah meal was mixed with oil and eggs and fried in oil, one blesses Mezonos. If he baked it, it is Pas Kisnin, so one blesses ha'Motzi only if he fixed a meal on it.

Kaf ha'Chayim (84): Beis Efrayim (OC 11,12) says that if bread was crumbed and kneaded again, even if it was baked, if it did not get the form of bread, one blesses Mezonos. Tosfos holds that it is bread, so one should eat it only in a meal.

Shulchan Aruch (ibid.): If it is not cooked or connected, just it is crumbed finely, even though it does not have a k'Zayis or the form of bread, one blesses ha'Motzi .

Beis Yosef (DH Amar): This is from reasoning. Since it is bread without any mixture of a liquid, it does not lose the law of bread. Rava requires the form of bread only for Chavitza, in which the crumbs are mixed with a liquid. Crumbs alone without any mixture, even if they are very fine, are always bread, and one blesses ha'Motzi.