Mousaka is an oven-baked food made of layers. From bottom to top you will find in your mοusaka:
The first, second, and third layers consist of potatoes, eggplants, and zucchini which have been fried in fresh olive oil.
Then comes a moisture layer of sliced meat and tomato sauce.
After that, there is a final layer of the white sauce (béchamel) made of butter, milk, and flour
And for a final touch, there is a top-rich layer of greek grated cheese (graviera).