Passover- A] Gebraucht- Baking Matzah with Liquid (Example- Pizza) B] Matzah Shemurah
The Mishna Berura brings down the custom of some communities that do not cook their Matzah on Pesach. The Ashkenazim call this Gebraucht. What does it mean? They will not take Matzah that was baked before the holiday or on the holiday, and put it into water, into a liquid, in things like that. They will not put it into a soup, or into cereal. Why? Because they are concerned that maybe there’s some flour in the dough that didn’t get cooked or baked. And therefore when you put it in liquid there is a chance for it to become Chametz.
The Mishna Berura says that we shouldn’t ridicule people that follow this Minhag, even though there is no reason why one would assume that the Matzah has unbaked flour in it. We don’t assume the worst, especially today that our Matzot are made like crackers. The other Matzot that they are talking about was thicker, and it had a bigger chance to not be fully cooked. But our Matzot today are practically burnt. So you don’t have to worry about flour. Therefore our Minhag is to allow Matzot to be dipped into water or another liquid item even on Pesach. Our Minhag allows to cook it and do anything you want to it. Once it is baked in the factory for the purpose of Mitzvat Matzah Pesach, then already we consider it complete and Kasher. (Yehave Daat Helek 1:21)
Now for the nights of the Seder, one must use Matzah Shemura. That means it was watched from the time of the cutting. That’s not the regular Matzot that you are buying in the boxes that are just kosher, or kosher for Pesach. It needs to be Kosher for Passover Matzah Shemura. Which means it has to say it on the box and have a special Hechsher that it was made Lishem Mitzvat Matzah. This must be used specifically for the first two nights.
For the rest of the holiday, a person doesn’t not have to be Makpid (strictly specific) to eat Matzah Shemura, even though some of the books bring down that the Gaon MeVilna held that if you eat Matzah Shemura the whole holiday, you fulfill a Mitzvah DeOrita (commandment form G-d). In the Lakewood Yeshivah, Rav Aharon Kotler was Makpid on this. In the Lakewood Yeshivah he would only serve on Pesach to the Yeshiva boys Matzah Shemura. Matzah Shemura is much more expensive than the regular Matzah but he rationalized and said that since the Gaon MeVilna says it is a Mitzvah DeOrita therefore it is worth it to spend a few extra dollars in order to fill this Mitzvah.