Soak the morels in 500 ml (approximately 2 cups) of water for about 30 minutes.
Cook the lasagna noodles according to package directions. Drain, rinse in cold water and drain again.
Peel and finely dice the shallots.
Rinse the celery and cut lengthwise into thin strips about 5 cm long (approximately 2 inches).
Peel the carrot and cut lengthwise into thin slices.
Blanch the tomatoes for a few seconds. Peel, quarter and remove the seeds.
Strain the morels through a filter and collect the soaking water.
Rinse the morels thoroughly under running water, then split into chunks.
Heat the clarified butter in a frying pan. Sauté the shallots and add the morels. Sauté briefly. Pour in the soaking water and the port wine. Boil over high heat to boil down slightly. Remove from the heat and set aside.
Blanch the carrots and celery in boiling salt water for about 2 minutes. Quench with colde water in a colander and drain.
For the white sauce, melt the butter in a pot and sauté the flour while stirring. Add the milk gradually, stirring constantly and vigorously. Simmer the sauce on low heat for about 15 minutes.
Stir in half the Parmesan. Season to taste with salt, pepper, nutmeg, and lemon juice.
Drain the mozzarella and cut into thin slices.
In a greased baking dish, place a layer of lasagna noodles. Top with some of the mushrooms, carrots, celery, tomatoes and mozzarella. Sprinkle with a little sauce. Continue to layer all of the ingredients this way. The final layer should consist of noodles. Pour the remaining sauce on top. Sprinkle with the remaining Parmesan and drizzle with oil.
Bake in a preheated oven (200°F (approximately 400°F)) for about 40 minutes. Bake until the lasagna is lightly browned.