Béchamel sauce is used in lasagna to add a creamy and rich texture to the dish, just like we did with this recipe. The sauce is made with butter, flour, milk, and seasonings, and it is traditionally used in Italian cuisine as a base for many dishes, including lasagna. Béchamel sauce is added between the layers of lasagna to help bind the ingredients together and keep the dish from becoming too dry. It also adds a delicious flavor to the lasagna that complements the other ingredients.