The Kaiser roll (German: Kaisersemmel), also called a Vienna roll (Wiener Kaisersemmel; as made by hand also: Handsemmel) or a hard roll, is a typically crusty round bread roll, originally from Austria. It is made from white flour, barm, malt, water and salt, with the top side usually divided in a rotationally symmetric pattern of five segments, separated by curved superficial cuts radiating from the centre outwards or folded in a series of overlapping lobes. The crisp Kaisersemmel is a traditional Austrian food officially approved by the Federal Ministry of Agriculture.
Kaiser rolls are thought to have been named to honor Emperor (Kaiser) Franz Joseph I of Austria (1830–1916) or after a Vienna master baker named Kayser, who had begun manufacturing crusty breadrolls about 1750. Indeed already in the 18th century, retail prices of Semmeln breadrolls were fixed by law in the Habsburg Monarchy. Allegedly the name Kaisersemmel came into general use, after in 1789 the bakers' guild had sent a delegation to Emperor Joseph II (1741–1790) and convinced him of decontrolling the selling price.
More probably the prefix Kaiser- may be derived from Italian: a la casa, "house-special". By all means, with the monarchal connotation, it stood out against common rolls known as Mundsemmeln ("mouth rolls") or Schustersemmeln ("cobbler rolls"). Kaiser rolls are traditionally found in Austria, but have also become popular in other countries of the former Austrian Habsburg Empire, such as Poland (known as kajzerka in Galicia), Slovenia (kajzerica), Croatia, Italy, Hungary (császárzsemle), as well as in Germany, the United States, and Canada. Italian bakers, during the Austrian domination in Lombardy, produced a hollow version known as michetta or rosetta.
Kaiser rolls today are largely produced by machine; the handmade variant is called a Wiener Kaisersemmel (Handsemmel) according to the Codex Alimentarius Austriacus standards collection.
There are multiple variants, differing in size and type of flour used. While a Kaiser roll is plain, similar rolls are sometimes sprinkled on top with poppy seeds, sesame seeds, pumpkin kernels, linseed or sunflower-seed. The Kaiser roll is often used as a bun for sandwiches (including hamburgers) or a slice of Leberkäse, but it is most often served with slices of Extrawurst and pickled gherkins (Wurstsemmel) or with a type of Wiener Schnitzel (Schnitzelsemmel). It is also a main part of a typical Austrian breakfast, usually served with butter and jam. A variation called a kummelweck (sometimes pronounced "kimmelweck" or "kümmelweck") is topped with kosher salt and caraway fruits, often as part of a beef on weck sandwich.