Add lentils to a double amount of boiling, salted water. Cook covered for around 15 minutes. Check occasionally and if all water has been soaked in and lentils need some more cooking time, add some water. Alternatively, you can cook in a larger amount of water and drain the water afterwards.

Cook onions, garlic, carrot and mushrooms in a large skillet, until the onions become translucent. Add a few tablespoons of water at a time so the vegetables don't stick.

Stir in lentils, tomato sauce, spinach and all the spices, and cook for a few more minutes, until the spinach has wilted.

Check the instructions on your lasagna sheets, and make sure to cook them beforehand if it is necessary.

Preheat the oven to 180C

Add some sauce to the bottom of the dish. Add a layer of lasagna sheets. Add a layer of sliced zucchini. Add a layer of sauce.

Repeat layers until you use up all the ingredients. Make sure that the sauce is on top.

Cover with aluminum foil and bake for 45 minutes.

If you want, sprinkle generously with breadcrumbs on top, and bake using the grill for several more minutes, until the breadcrumbs are golden.

We normally eat this the minute it comes out of the oven, but it's good to let it cool for a little while before serving, because it firms up a little bit when it cools.