Crisp bread (Swedish: knäckebröd, hårt bröd, spisbröd, Danish: knækbrød, Norwegian: knekkebrød, Finnish: näkkileipä) is a flat and dry Nordic type of bread or cracker, containing mostly rye flour. It is popular in armies and schools because of its light weight and simple, transport-friendly shape. Also, it is very cheap and if stored in dry conditions it will keep fresh and edible for a very long time. Crisp bread is a staple of Nordic cuisine and was for a long time considered a poor man's diet. However, in recent years there has been renewed interest in crisp bread in the Nordic countries.
Traditionally, this was done by mixing crushed ice into the dough, which then evaporated during baking. Today, the dough, which must contain a large amount of water, is cooled and mixed until bubbly.
Another method is to knead the dough under pressure in an extruder. The sudden drop in pressure then causes water to evaporate, creating bubbles in the dough.
Crisp bread is only baked for a few minutes, at temperatures usually between 200 and 250 °C.