Cook the pasta as instructed on the package.

Pour the olive oil into a deep pan and stir-fry the zucchini. Add some salt and pepper, and saute at low heat for 5 minutes. Take them out and repeat the process with the onion, and once more with the mushrooms.

Stir-fry the crushed tomatoes with oregano and a pinch of salt until it looks like a paste. Add some more olive oil if you need it to look more smooth.

Boil the spinach for a couple of minutes (add a bit of salt to the water). Then put the spinach in cold water to stop the cooking so the leaves stay green.

Take a casserole, spread a thin layer of tomato paste on the bottom, and start building the lasagna: place a layer of lasagna sheets, then a layer of mixed vegetables, then mushrooms, then spinach. Next, add a layer of tomato paste and then a layer of mozzarella. Repeat all the layers until you run out of ingredients.

Sprinkle parmesan and oregano on top and bake for 20 minutes in a preheated oven at 180ºC.