Lasagne, or the singular lasagna, is an Italian dish made of stacked layers of thin flat pasta alternating with fillings such as ragù (ground meats and tomato sauce), vegetables, cheese (which may include ricotta and parmesan), and seasonings and spices such as garlic, oregano and basil. The dish may be topped with melted grated mozzarella cheese. Typically, the cooked pasta is assembled with the other ingredients and then baked in an oven. The resulting lasagne casserole is cut into single-serving square portions.
Lasagne originated in Italy during the Middle Ages and has traditionally been ascribed to the city of Naples.
The traditional lasagne of Naples, lasagne di carnevale, are layered with local sausage, small fried meatballs, hard-boiled eggs, ricotta and mozzarella cheeses, and sauced with a Neapolitan ragù, a meat sauce.
Lasagne al forno, layered with a thicker ragù and Béchamel sauce, and corresponding to the most common version of the dish outside Italy, are traditionally associated with the Emilia-Romagna region of Italy.
In other regions, lasagne can be made with various combinations of ricotta or mozzarella cheese, tomato sauce, meats (e.g., ground beef, pork or chicken), and vegetables (e.g., spinach, zucchini, olives, mushrooms), and the dish is typically flavoured with wine, garlic, onion, and oregano. In all cases, the lasagne are oven-baked (al forno).
In the northern Italian region of Emilia-Romagna, and especially in its capital, Bologna, layers of lasagne are traditionally green (the color is obtained by mixing spinach or other vegetables in the dough) and served with ragù (a thick sauce made from onions, carrots, celery, finely ground pork and beef, butter, and tomatoes), bechamel and Parmigiano-Reggiano cheese.
According to en.wikipedia.org