Gemara

41b: The only thing that requires a blessing beforehand but not afterwards is Pas ha'Ba b'Kisnin.

42a: Rav Huna ate 13 loaves. Each was (the volume of eight eggs, i.e.) a third of a Kav. He did not bless on them.

(Rav Nachman): He ate these due to hunger. Since others fix a meal on such an amount, he must bless on them!

(Beraisa - R. Muna): One blesses ha'Motzi on Pas ha'Ba b'Kisnin.

(Bei Rav Yehudah bar Chaviva citing Shmuel): The Halachah follows R. Muna.

(Rav Yehudah): Shmuel said that the Halachah does not follow R. Muna!

Shmuel said that one may use Lachmaniyos to make an Eruv, and one blesses ha'Motzi on them, i.e. when one fixed his meal on them. If not, he does not bless ha'Motzi.

Rishonim

Rambam (Hilchos Berachos 3:9): If a dough was kneaded with honey, oil or milk, or he mixed in spices and baked it, this is called Pas ha'Ba b'Kisnin. Even though it is bread, he blesses on it Borei Minei Mezonos. If he fixed his meal on it, he blesses on it ha'Motzi.

Talmidei R. Yonah (29a DH she'Ein): Rashi says that Pas ha'Ba b'Kisnin is a certain kind of bread that was normally eaten after parched grain. It had much spices, so it was not normal to eat so much of it. Therefore, it requires a Berachah beforehand but not afterwards. He explains that Pas ha'Ba b'Kisnin is the only thing that requires beforehand the Berachah Borei Minei Mezonos, but afterwards we do not say Al ha'Michyah, rather, Borei Nefashos. He needed to say so, for he explains that whenever one eats it, even not in a meal, he does not bless after it. We cannot say that he does not bless afterwards at all. (Rather, he blesses Borei Nefashos Rabos.) This is wrong. Since one must bless Borei Nefashos, how can we say that one does not bless after it?! This is the proper Berachah, since people do not eat much of it! The Tosafists asked that also rice and millet require Borei Minei Mezonos beforehand and Borei Nefashos afterwards. Rather, Pas ha'Ba b'Kisnin is like R. Chananel says. It is a dough made with a pocket, and they put in it almonds, honey, and sweet things. It is brought after the food. Therefore it needs a Berachah beforehand, but Birkas ha'Mazon exempts it from a Berachah Acharonah. R. Yonah says that we can say that one eats it in the middle of a meal, like the Gemara connotes. Since it is not for satiation, rather, a kind of sweet, regarding a Berachah Rishonah it does not join with the bread, which is eaten for satiation. One does not bless afterwards, for it is secondary with other things (eaten with the bread), and Birkas ha'Mazon exempts it. [Also] what the Tosafists said is true. If one ate if after the food, he must bless beforehand.

Poskim

Shulchan Aruch (OC 168:7): Some say that Pas ha'Ba b'Kisnin is made like pockets, filled with honey, sugar, nuts or spices. Some say that it is a dough in which were mixed honey, oil, milk or spices and it was baked, and the mixture of fruit juice or spices is recognized in the dough.

Magen Avraham (15): Even though the filling is primary and people do not intend for the filling, grain is important, therefore one blesses Borei Minei Mezonos. However, if one eats only the fruits inside, he blesses on it Borei Peri ha'Etz.

Rema: Some say that this is proper bread, unless there are so much spices or honey that they are primary. This is the custom.

Kaf ha'Chayim (58): The Ashkenazim follow the Rema, and Sefardim are lenient like the Mechaber. However, one who fears Shamayim should fulfill both opinions and eat them only in a meal, or eat as much as others fixed his meal on them, and bless ha'Motzi on them.

Shulchan Aruch (ibid.): Some say that it is bread, whether or not it was seasoned, made like thick, dry biscuits, and one chews them. The Halachah follows all of these. They all get the law of Pas ha'Ba b'Kisnin.

Beis Yosef (DH v'Rashi): The Aruch brought from Rav Hai Gaon that Pas ha'Ba b'Kisnin is dry biscuits. People normally eat a little. When Rav Huna ate much, Rav Nachman said that he ate due to hunger, to be satiated from it, and not like Kisnin. Therefore, he needed to bless afterwards.

Beis Yosef (ul'Inyan): This is a Safek about a mid'Rabanan matter, so we are lenient like all of the opinions. Whether they are pockets filled with honey and almonds, or a dough in which was mixed with fruit juice or spices, all of them are Pas ha'Ba b'Kisnin, and one blesses ha'Motzi only if he fixed his meal on them, or ate as much as people fix on.

Question (Bach Od): Why does the Beis Yosef say that it is a leniency to bless Borei Minei Mezonos? If he says the wrong Berachah, in either case he transgresses saying Hash-m's name in vain! Rather, one should eat the dry biscuits only in a meal, unless the majority is honey. However, some argue also about this! Therefore, one should eat them only in a meal, unless there is more honey and spices than flour.

Answer #1 (Drishah 2): Borei Minei Mezonos is a general (all-encompassing) Berachah, just like sheha'Kol. Therefore, we bless Borei Minei Mezonos on all of them. We are lenient about the Berachah Acharonah to shorten it and bless only me'Ein Shalosh, even though it is not in place of the three Berachos (of Birkas ha'Mazon).

Answer #2 (Taz 6): The Bach's question is not difficult. Borei Minei Mezonos exempts even a dough, for it sustains. Ha'Motzi and three Berachos were enacted due to the importance of bread. If we are unsure whether it has this importance, we should be lenient not to require ha'Motzi. This is also a stringency not to say ha'Motzi and three Berachos without need.

Kaf ha'Chayim (63): Orchos Chayim says that there are several kinds of Safek Pas ha'Ba b'Kisnin, and we bless Borei Minei Mezonos on them. Therefore, if one cannot wait to eat such Mezonos in a meal, he blesses Borei Minei Mezonos and Al ha'Michyah.

Question (R. Akiva Eiger): Why didn't the Mechaber write that one who fears Shamayim should fulfill all opinions, like he wrote in Sa'if 13?

Answer (Bi'ur Halachah DH v'Halachah): Ma'amar Mordechai says that since the Poskim do not explicitly argue about this, perhaps they agree with each other (and all of these are Pas ha'Ba b'Kisnin). The Taz resolved the Bach's question. Many Acharonim hold like the Rema; it suffices if it is kneaded with mostly honey and a minority of water.

Kaf ha'Chayim (64): The Mechaber did not say that one must eat it only in a meal, because this is not a Safek law. Not everyone says so (that the Poskim argue with each other - PF). He said so about water in which raisins were soaked (202:1), for there Poskim explicitly argue. Even there, he said only that one who fears Shamayim should be stringent. Also, it is very common to eat Pas ha'Ba b'Kisnin outside a meal, and not everyone can be careful about this. Also, even if one eats it in a meal for dessert, he must bless on them. If he will not bless, he benefits without a Berachah! However, for this it would help to intend for the Pas Kisnin when blessing ha'Motzi. Even without special intent, we can say that ha'Motzi exempts Borei Minei Mezonos. Therefore, one who wants to be stringent can eat them in a meal.

Bi'ur Halachah (8 DH Te'unim): The Magen Avraham says that also Pas ha'Ba b'Kisnin eaten in a meal requires a Berachah Rishonah. Several Rishonim say so. This is letter of the law. However, we have a Safek what is Pas ha'Ba b'Kisnin! Even though the Mechaber ruled to be lenient about all of them, this is because we are lenient about a Safek mid'Rabanan. Therefore, we do not say ha'Motzi and Birkas ha'Mazon. Here, it is unreasonable to establish it to be Pas ha'Ba b'Kisnin and obligate a Berachah Rishonah during a meal. Just the contrary, we should be lenient about a Safek mid'Rabanan. Perhaps it is bread, and ha'Motzi exempted it! Therefore, one blesses in a meal only if it is Pas ha'Ba b'Kisnin according to all opinions, i.e. it is filled, kneaded with honey or similar things, and it is thin and dry. Dagul me'Revavah, the Graz, R. Akiva Eiger and the Chayei Adam say so. The question was not so difficult according to the Ma'amar Mordechai, for perhaps all agree that all of these are Pas ha'Ba b'Kisnin. In practice, one should not bless on cake kneaded with honey, eggs or similar things, or on dry biscuits, even if they are for dessert. One who blesses on cakes filled with Peros does not lose, for most Poskim hold that this is Pas Kisnin. The Chayei Adam connotes that it is proper to intend that ha'Motzi exempt even cake kneaded with honey.

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.