Ciabatta (Italian pronunciation: [t?a'bat?a], literally "carpet slipper") is an Italian white bread made with wheat flour and yeast. The loaf is somewhat elongated, broad and flattish and, like a slipper, should be somewhat collapsed in the middle. Since the late 1990s it has been popular across Europe and in the United States, and is widely used as a sandwich bread. Ciabatta was first produced in Liguria, although at least one type of ciabatta can be found in nearly every region of Italy nowadays. The ciabatta from the area encompassing Lake Como has a crisp crust, a somewhat soft, porous texture, and is light to the touch. The ciabatta found in Tuscany, Umbria, and Marche varies from bread that has a firm crust and dense crumb, to bread that has a crisper crust and more open texture. The more open-crumbed form, which is usual in the United States, is made from a very wet dough, often requiring machine-kneading, and a biga or sourdough starter. There are many variations of ciabatta. When made with whole wheat flour, it is known as ciabatta integrale. In Rome, it is often seasoned with olive oil, salt, and marjoram. When milk is added to the dough, it becomes ciabatta al latte. A toasted sandwich made from small loaves of ciabatta is known as a panino (plural panini). The fast food chain Jack in the Box offers a line of sandwiches that use a ciabatta-like bread in place of a hamburger bun, and refers to the entire sandwich as a ciabatta. Carl's Jr.'s prime rib burger is also made on ciabatta bread. The bakery-cafe franchise Panera Bread offers several sandwiches on ciabatta, including their breakfast egg, bacon, and cheese sandwiches. McAllister's Deli also offers several sandwiches on ciabatta bread. McDonald's in Canada also offers a line of ciabatta sandwiches, like the Angus Burger and the Crispy Chicken Classic.