I made a 2/3 size lasagna the other day with some leftover bolognese sauce from another dish.  I didn’t have much sauce so I added leftover smoked pork to it to stretch it out a bit.  Worked fine!The lasagna recipe, otherwise, was basic.  Ricotta cheese with an egg, Parmesan, mozzarella, and a scant sprinkle of cheddar from that last little bit in a bag, as a nod to the smoked pork.