Gemara

(Rav and Shmuel): One blesses Borei Minei Mezonos on anything containing [any of] the five species of grain.

39a (Rav Ashi citing Rav Kahana): Little flour is added to a cooked beet dish, so we bless on it Borei Pri ha'Adamah. Much flour is added to a cooked turnip dish, so the blessing is Borei Minei Mezonos.

Retraction (Rav Kahana): We bless Borei Peri ha'Adamah on both of them. Much flour is added merely to make it stick together.

Rishonim

Rambam (Hilchos Berachos 3:6): If turnips or cabbage were cooked, and one added flour of one of the five grains in order to make it stick together, we do not bless on it Borei Minei Mezonos. The turnip is Ikar and the flour is Tefel. Anything mixed in to make a food stick or to give scent or color is Tefel. If it (the flour) is added to give taste, it is Ikar. Therefore, honey that is cooked and they put in Chelev (the best part of) wheat in order to make it stick together, and make sweets from it, we do not bless on it Borei Minei Mezonos, because the honey is Ikar.

Rosh (6:7): Whenever the Ikar is from the five grains, even if the majority is from another species, we bless on it Borei Minei Mezonos and afterwards Al ha'Michyah. However, if flour is put in a Tavshil to congeal it or make it stick together, this is not considered Ikar, like we say about a beet dish.

Tosfos (36b DH Kol): When they put flour into beans or lentils, or into almonds for a Choleh, if it is for sustenance, the one blesses Borei Minei Mezonos. If it is merely in order to make it stick together, one need not bless Borei Minei Mezonos. It is good to eat it only within a meal after ha'Motzi, and it is exempt in any case.

Shitah Mekubetzes (39a DH v'Lo): When the flour is added in order to eat it, Even if there is a little, one blesses Borei Minei Mezonos. However, this is only if there is k'Zayis bi'Chdei Achilas Pras. If not, it is not important at all.

Poskim

Shulchan Aruch (OC 208:2): If the five grains were cooked, even if he mixed in much more honey or other species than grain, he blesses on it Borei Minei Mezonos and afterwards Al ha'Michyah. If he added grain only in order to make it stick together or solidify it, it is Batel in the Tavshil.

Beis Yosef (DH u'Mah she'Chasav Rabeinu): The Rashba (36b DH Duvsha) says that "honey is Ikar" means that it is the majority over the flour, or the Tavshil is mainly for the sake of the honey. The flour is merely to give taste and improve it. Even so, since the flour is in order to be Machshir it, we bless on the flour, like Rav and Shmuel taught. This is unlike a Tavshil of turnips. Even though it has much flour, we bless on it only sheha'Kol. There, the flour is not to be Machshir it and give taste. It is merely to make it stick together. Here, the flour is Ikar, so we bless on it.

Bach (2): If the grain is only to make it stick together, even if it is the majority, he blesses the Berachah of the other species, like we say about turnips and beets.

Kaf ha'Chayim (12): The Taz (4) says that one should not be so lenient when grain is the majority, since he gets much benefit from it. Also Mateh Yehudah says that when it is to stick together, this annuls the special importance of grain, but this does not override if the majority is grain. If such a case occurred, one should eat it only in a meal, or bless on a food that is Vadai Borei Minei Mezonos, and on a food with the Berachah of the other species, to avoid the Safek.

Mishnah Berurah (8): This is when the grain is not for taste or satiation, only to make the Tavshil stick together. It is not important, and it is Batel to the Tavshil, even if he put in much flour.

Shulchan Aruch (3): When they put flour into almonds for a Choleh, if it is for sustenance, the one blesses Borei Minei Mezonos. If it is merely in order to make it stick together, one does not bless Borei Minei Mezonos. It is good to eat it only within a meal after ha'Motzi, and he (or it) is exempt Mimenah (from it).

Taz (6): Mimenah is a printing mistake. It should say Mimenu (in any case), like it says in Tosfos.

Beis Yosef (DH Kasuv): Shibolei ha'Leket says that the same applies to flour put into grits or rice cooked with honey, in order to congeal it. It is Batel, and one does not bless on it.

Taz (5): Why did Tosfos say to be Yotzei the Safek through having it in a meal, and not blessing on it? He could have said to bless on it sheha'Kol, for then one is Yotzei in any case! The Tur said that sheha'Kol could resolve the Berachah Rishonah, but the only solution for the Berachah Acharonah is to eat it in a meal. Here we discuss the Berachah Rishonah! We must say that also here, the Safek was due to the Berachah Acharonah. Therefore, if one will eat less than a k'Zayis, he may eat it outside a meal and bless sheha'Kol.

Kaf ha'Chayim (17): Nehar Shalom says that even for the sake of the Berachah Rishonah, it is better to eat it in a meal than to bless sheha'Kol due to Safek.

Mishnah Berurah (12): If it is so soft that one drinks it, even if the flour is for sustenance, one blesses sheha'Kol (Sa'if 6).

Mishnah Berurah (13): The Acharonim ask why one is Yotzei in any case. If the flour is Batel to the almonds, one must bless on Peros in a meal! It seems that since he is sick, he bases his meal on them. One who bases a meal on Peros does not bless on them (177:3).

Shulchan Aruch (OC 208:9): If one mixed flour of millet or other legumes with flour of the five grains and cooked it in a pot, if there is not k'Zayis of the grain flour bi'Chdei Achilas Pras he does not say Birkas ha'Mazon afterwards, but he says ha'Motzi beforehand since it has the taste of grain, even though there is not k'Zayis bi'Chdei Achilas Pras. Afterwards, he blesses Al ha'Michyah. For what was cooked it in a pot, he blesses Borei Minei Mezonos beforehand and Borei Nefashos afterwards.

Magen Avraham (15): All agree that the laws of Chalah and ha'Motzi depend on each other. Regarding Chalah it says "Lechem". The Gemara (Berachos 37a) equates Matzah to ha'Motzi. Also the Rambam (Hilchos Chametz 6:7) says that one is Yotzei Matzah only with bread on which one blesses Birkas ha'Mazon. If so, according to the Magid Mishneh and those who agree with him, one blesses Birkas ha'Mazon on a mixture of rice and grain even if there is not k'Zayis grain bi'Chdei Achilas Pras. Regarding other species (than rice), they are not called bread regarding ha'Motzi or Birkas ha'Mazon. The Shulchan Aruch is difficult. We never find that one blesses ha'Motzi beforehand without Birkas ha'Mazon afterwards! We must say that regarding Isurim, one is exempt if he did not eat k'Zayis bi'Chdei Achilas Pras. Likewise, one blesses Birkas ha'Mazon only if he ate k'Zayis [of grain] bi'Chdei Achilas Pras. He does not eat this amount [if he eats normally], for the k'Zayis of grain is mixed with a Pras. One blesses ha'Motzi for any amount. However, if they do not join, why does he say Al ha'Michyah afterwards? After other species one blesses only Borei Nefashos. Regarding Chalah, if there is less than k'Zayis of grain bi'Chdei Achilas Pras, it is Batel. We must say that regarding Berachos, one blesses Al ha'Michyah on anything with grain, even if there is not k'Zayis bi'Chdei Achilas Pras. Why does the Shulchan Aruch says to bless Borei Nefashos after mixtures of flour cooked in a pot? We find this only regarding rice! However, if it was not mixed with flour, rather, with other species, he blesses Al ha'Michyah even if there is not k'Zayis bi'Chdei Achilas Pras.

Avnei Nezer (OC 38:8): The Shulchan Aruch rules like R. Yonah, that one blesses Borei Minei Mezonos even if there is not k'Zayis bi'Chdei Achilas Pras, but afterwards he blesses only Borei Nefashos. The Magen Avraham says that if grain flour was mixed with things other than flour, one blesses Al ha'Michyah afterwards even if there is not k'Zayis bi'Chdei Achilas Pras. Ma'adanei Melech and Eliyahu Rabah do not distinguish whether it was mixed with flour or other things. This is more reasonable.

Avnei Nezer (14): The Shitah Mekubetzes on Berachos had not spread in the days of the Shulchan Aruch. Had the Beis Yosef seen it (that he says that if there is not k'Zayis bi'Chdei Achilas Pras, the flour is Batel) he would not have entered a Safek to say ha'Motzi, since according to the Shitah Mekubetzes he is not Yotzei through this. It is better to bless sheha'Kol, for then Vadai one is Yotzei.