The classic, proper version, cotoletta alla milanese is made from milk-fed veal, using meat with a bit of the rib bone as in a chop (costaletta) still attached, then dredged in egg and breadcrumbs and fried in butter and oil. Outside of Milan, it's generally pounded as thin as its cousin, Wiener schnitzel (cotoletta alla viennese in Italy), and served without the bone, which for a Milanese is properly called a cotoletta all''orecchio di elefante ('elephant's ear').
In Sicily, cotoletta alla palermitana is similar, but brushed with olive oil instead of egg, breaded, and then grilled.
cotoletta alla valdostana: two thin slices of veal with fontina cheese and ham in between, breaded and fried.
cotoletta bolognese (or petroniana): breaded and fried, with a slice of ham, truffle and melted parmigiano on top.
cotoletta di fegato: breaded and fried calf's liver