Pas Ha'boh Be'kisnin (Brachah on Pizza and the Like) \Parashat Eikev
In general, the various Brachos we recite on food are a Rabbinic requirement. An exception to this is found in this week's Parsha. The famous Passuk in Parshas Eikev says "ve'ochalta ve'savahtah u'veirachta etc." which is the Torah-obligation of Bircas Hamazon, Bentching after eating bread.This raises the issue of the precise definition of bread in Halachah.
There's an important category of bread called Pas Ha'boh Be'kisnin. The basic idea of this is a kind of bread that is not prepared in the usual satiating way of regular bread, rather made in a more snack-like manner. Eating such a bread does not automatically require one to Bentch afterward (as well as Netillas Yadayim and Hamotzie beforehand), rather is dependent on how much is eaten. Only if one eats an amount worthy of a meal is Pas Haboh Bekisnin considered to be a replacement of the usual bread and requires Bentching.
As to the actual definition of Pas Haboh Bekisnin there is dispute amongst the Rishonim. There are three different definitions given. One, a filled pastry, such as a pie or a fruit-filled croissant. Two, a bread prepared from a dough with a significant amount of ingredients aside from flour and water, such as cake and the like. And three, a bread with a dry, crumbly consistency, such crackers or pretzels. According to the standard understanding these three opinions disagree with each other, meaning that according to each opinion the other two types are considered to be regular bread. Only something that meets all three credentials, such as a pie with a sweetened, crumbly crust, would be considered a definite Pas Haboh Bekisnin.
Being that, as mentioned, Bentching is a Torah-obligation, one would expect that this would be a case of a Safek De'oraissah, meaning a question regarding a Torah law, which generally requires us to be stringent on the matter. So being, one would need to Bentch on all cakes and crackers and the like. The Halachah, though, is not this way, rather, as long as one of the above qualifications are met the food is not deemed as bread and requires only a Mezonos and Al Hamichya. One explanation offered for this is that, although one is absolutely required by Rabbinic law to recite the full Bentching on bread, to fulfil his Torah obligation it indeed suffices to recite just Al Hamichyah. As such, even would the food really be considered to be actual bread the person indeed has fulfilled his Torah obligation with Al Hamichyah as well. Another explanation given, mentioned in the Bi'ur Halachah 168, 7, is that the three opinions don't necessarily disagree with one another, rather, each gave an example of an atypical type of bread, one that's main purpose is not for satiation. All three examples, though, are really agreed upon and there is actually no Safek (uncertainty) at all with regard to Bentching
Another relevant ramification of these bread-qualifications is whether one needs to recite a Brachah of Mezonos when eating cake or the like for dessert at the end of a bread-meal. In general, dessert foods, foods that are not served for the purpose of satiation, such as fruit and candy, are not exempted by the Brachah of Hamotzie said on the bread and require their own Brachah. Being so, (unless served also for satiation) cakes and cookies served for dessert should really require their own Brachah. If, however, we understand that the Brachah on these foods is actually a matter of uncertainty, and they might actually really be a Hamotzie, then we cannot make another Brachah on them even if eaten for dessert. This is because anything that is Hamotzie was definitely exempted by the Brachah said on the bread at the beginning of the meal. This depends on the two explanations cited above. See Bi'ur Halachah 168, 8.
Most Poskim rule that one should not say a Brachah on these foods during a meal, considering them a possible Hamotzie. The Bi'ur Halachah cites from the Chayei Odom that, ideally, one should have these foods specifically in mind when he recites the Hamotzie at the beginning of the meal. Another way for one to absolve himself of any question would be to say a Mezonos on something right before the meal, having in mind to exempt the cake he'll be eating for dessert. Again, even without doing so, though, one does not make another Brachah on the cake for dessert.
Another issue of dispute is the Shiur (amount) of food that requires Hamotzie even for Pas Haboh Bekisnin. Some rule that once one eats 3-4 eggs-worth of Pas Haboh Bekisnin he is required to Bentch. Others rule that the Shiur is dependent on the normal amount eaten for a meal for each person's specific age group. For instance, a young child might need to Bentch on even one slice of pizza, whereas an adult might require two or more. Ideally, the Mishnah Berurah rules, one should try and refrain from eating 4 eggs-worth of pas Haboh bekisnin. The strict Halachah, though, is like those that rule that it depends on the amount normally eaten for a meal in each persons specific age group.
One more relevant dispute is between the Taz and the Magen Avraham at the end of Siman 168. The Magen Avraham sides with the opinion of the Shlah who maintains that this that a filled dough is considered to be Pas Haboh Bekisnin is only when it is filled with a sweet filling. If, however it is filled with meat, fish or cheese and the like, which are meal-type foods themselves, it retains its bread status and requires Hamotzie and Bentching like any other bread. The Taz argues that there is no difference between kinds of fillings and even when filled with meat and the like it has the status of pas haboh bekisnin. The Mishnah Berurah sides with the Magen Avraham. Poskim note, however, that often in such a case, like with bourekas and pizza and the like, the food has the status of Pas Haboh Bekisnin for a different reason - that the dough is prepared with mostly liquids other than water.
