Slice the eggplants and zucchini lengthwise into 1/2-inch (about 1 cm) thick strips.

Arrange the zucchini slices on a baking sheet, drizzle with a little olive oil and sprinkle with salt. Bake at 400°F (200°C) with convection for 15 minutes. Finish under the broiler for a bit of color.

Drain the eggplants, arrange them on a baking sheet, drizzle with a little olive oil and sprinkle with salt. Bake in a preheated oven at 400°F (200°C) with convection for 10-15 minutes. Finish under the broiler for color.

Peel the potatoes and cut them lengthwise into 1/2-inch (about 1 cm) thick slices. Soak briefly in water, then drain. Arrange on a nonstick baking sheet and bake in a preheated oven at 400°F (200°C) with convection for 15 minutes.

The next day, wash and finely chop the mushrooms.

Prepare the filling: Sauté the onion and garlic in the oil until lightly golden, then add the mushrooms.

Sauté until the mushrooms release their liquid, then cook over high heat until most of the liquid evaporates. Deglaze with the wine.

Add the crushed tomatoes, tomato sauce, cinnamon, bay leaf, allspice, salt, and pepper. Lower the heat and simmer until the sauce thickens. It should not be watery. Remove the cinnamon, bay leaf, and allspice at the end.

Grease a square baking dish or casserole with olive oil and sprinkle with a little breadcrumbs.

Layer the potatoes on the bottom of the dish, sprinkle with salt and pepper, then add a layer of zucchini, again seasoning with salt and pepper, and finally a layer of eggplants, arranging them in the opposite direction of the zucchini.

Spread the mushroom tomato sauce over the vegetables, then add another layer of eggplants on top.

For the béchamel: Boil the potatoes in salted water until very soft (they should mash easily). Reserve the potato cooking water in one container and place the potatoes in another bowl (do not discard the cooking water).

In a clean pot, add the reserved potato water (as specified in the recipe), the vegetable bouillon, and the potatoes. Heat the pot. Once the bouillon dissolves, blend everything with an immersion blender to make a potato soup.

In another pot, heat the olive oil. When hot, add the flour and stir constantly over medium heat for about 2 minutes until lightly golden. Remove from heat and gradually add the potato water, stirring constantly.

Preheat the oven to 350°F (180°C).

Return the pot to the heat and stir constantly until the mixture thickens and resembles béchamel. Stir in the nutmeg, salt, and pepper at the end. The béchamel should be pourable, not too thick.

Spread the béchamel over the eggplants, sprinkle the top with breadcrumbs and a little more nutmeg if desired, and bake the moussaka for about 1 hour until the top forms a crust. Let it cool slightly before cutting.

Enjoy!