Cannelloni are a cylindrical

Cylinder (geometry)

A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

 type of pasta generally served baked with a filling and covered by a sauce. Some type of cannelloni need to be boiled beforehand, for some others is enough to use runnier sauces/filling.
If one cannot find ready made cannelloni, rolling lasagne around a filling is an alternative.
The stuffing may include ricotta

Ricotta

Ricotta is an Italian dairy product made from sheep milk whey left over from the production of cheese. Although typically referred to as ricotta cheese, ricotta is not properly a cheese because it is not produced by coagulation of casein...

 cheese, spinach

Spinach

Spinach is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant , which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions...

 and various kinds of meat

Meat

Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...

. The sauce

Sauce

In cooking, a sauce is liquid, creaming or semi-solid food served on or used in preparing other foods. Sauces are not normally consumed by themselves; they add flavor, moisture, and visual appeal to another dish. Sauce is a French word taken from the Latin salsus, meaning salted...

s typically used are tomato

Tomato sauce

A tomato sauce is any of a very large number of sauces made primarily from tomatoes, usually to be served as part of a dish...

 or béchamel

Béchamel sauce

Béchamel sauce , also known as white sauce, is one of the mother sauces of French cuisine and is used in many recipes of Italian cuisine, for example lasagne. It is used as the base for other sauces . It is traditionally made by whisking scalded milk gradually into a white roux...

 sauce.

Versions

Cannelloni is often erroneously referred to as manicotti (ˌmænɨˈkɒtiː), which is actually a filled Italian dinner crepe, as opposed to pre-rolled pasta. While manicotti and cannelloni are sometimes used interchangeably in preparing non-traditional versions of some dishes, in traditional Italian cooking cannelloni are made with pasta and manicotti with a specialized crepe pan, and the two have particular uses. Although both terms are plural nouns in Italian, the English term is often construed as singular, particularly when used as the name of the dish. Also know in foreign countries as "canned bologna"

Traditions

St. Stephen's Day

St. Stephen's Day

St. Stephen's Day, or the Feast of St. Stephen, is a Christian saint's day celebrated on 26 December in the Western Church and 27 December in the Eastern Church. Many Eastern Orthodox churches adhere to the Julian calendar and mark St. Stephen's Day on 27 December according to that calendar, which...

 on December 26 is a traditional holiday

Traditions of Catalonia

There are quite a number of festivals and traditions in Catalonia. While most are of ancient origin, certain traditions are of relatively recent introduction. There are also some that are common to the whole Catalan society, but others are relevant only to a particular location...

 in Catalonia

Catalonia

Catalonia is an autonomous community in northeastern Spain, with the official status of a "nationality" of Spain. Catalonia comprises four provinces: Barcelona, Girona, Lleida, and Tarragona. Its capital and largest city is Barcelona. Catalonia covers an area of 32,114 km² and has an...

. It is celebrated right after Christmas

Christmas

Christmas or Christmas Day is an annual holiday generally celebrated on December 25 by billions of people around the world. It is a Christian feast that commemorates the birth of Jesus Christ, liturgically closing the Advent season and initiating the season of Christmastide, which lasts twelve days...

, with a feast including canelons. They are stuffed with ground meat from the escudella i carn d'olla

Escudella

Escudella is a Catalan stew.It is characterized by the use of sausages called botifarra or pieces of meat spiced with peppers.Additionally, beans, potatoes, and cabbage, as as other types of meat, can be used....

, turkey

Turkey (bird)

A turkey is a large bird in the genus Meleagris. One species, Meleagris gallopavo, commonly known as the Wild Turkey, is native to the forests of North America. The domestic turkey is a descendant of this species...

 or capon

Capon

A capon is a rooster that has been castrated to improve the quality of its flesh for food.-History:The Romans are credited with inventing the capon. The Lex Faunia of 162 BC forbade fattening hens in order to conserve grain rations. In order to get around this the Romans castrated roosters, which...

 of the previous day (Christmas dinner).

Other uses

The American composer Peter Schickele

Peter Schickele

Johann Peter Schickele is an American composer, musical educator, and parodist. He is best known for his comedy music albums featuring his music that he presents as music written by the fictional composer P. D. Q...

 has called for an uncooked cannelloni tube, which he calls "pastaphone", to be used as a musical instrument (played in the manner of a horn

Horn (instrument)

The horn is a brass instrument consisting of about of tubing wrapped into a coil with a flared bell. A musician who plays the horn is called a horn player ....

) in works by the fictional composer P. D. Q. Bach

P. D. Q. Bach

P. D. Q. Bach is a fictitious composer invented by musical satirist "Professor" Peter Schickele. In a gag that Schickele has developed over a five-decade-long career, he performs "discovered" works of this forgotten member of the Bach family...

.