We don't currently have any ricotta or cottage cheese to use in our lasagna so I use a bechamel sauce with parmesan cheese added. Also, we use the standard Mozzarella cheese.
Sometimes the 'white' layer tends to disappear altogether when cooking the lasagna except for maybe seeing some stretchy white stuff here and there. You would probably be interested to know the classic lasagna has ricotta and bechamel sauce for the 'white' part and later people used what they liked best like cottage cheese. I prefer ricotta, but alas there is none of either.
Hope you enjoy it anyway...and zucchini was in the veggie one that was offered.