The mitzvah of Matzah
Matza-Unleavened Bread, is also called Lechem O'ni- Bread of the poor and signifies our emunah, faith in G-D almighty. The Arizal Z"L and many more of our sages have emphasized the importance of participating in the baking of one's own Matzah. The Chida Z"l writes that by baking matzah we are able to destroy our harmeful spirits and have a fulfilling year.
Matzah, especially the Matzah that we eat at the Seder night, needs to be protected from leaviing from the harvest of the wheat till the final baking of Matzah. The Matzah needs to also be prepared for the sake of " Matzot Mitzvah". For that reason, Machine matzah are not sufficient to fullfill the Mitzvah of Matzah on the Seder night.
Matzah in previous years has been predominatly made into thin crackers. However, the Shulchan Aruch and various rabbis of our generatin as well have stated that matzah can be as thick as a tefach (3.5 inches) provided it is sufficiently baked to prevent leavening after it is removed from the oven.While our Matzaha's are not even close to being one inch thick, a softer version of Matzah is allowed to consumed even for Ashkenazis.
Here is Rabbi Shachter's (OU) answer regarding the Ashkenazi custom :
The Shmurah flour is kept seperate from any moisture untill the beginning of the 18 minutes. The water is special water, "Mayim Shelanu", that was allowed at least 12 hours to settle down. The mixture is mixed by hand and then kneaded and rolled. Before we place the Matzah in the oven we create holes in the dough, to allow an even bake through the Matzah. The Matzah is then baked in a wooden stove that reaches temperatures well over 1200 degrees F. Intrests you ? come join us !