Ingredients

Garnish
30 g dried porcini or matsutake mushrooms
400 ml of water
5 tbsp. unsalted butter
1 tbsp. thyme
800 g other species of fresh mushrooms of your choice
2 tbsp. fresh chopped tarragon
4 tbsp. fresh chopped parsley
Salt and white pepper

Lasagna
1 small chopped French shallots
5 c. to s. unsalted butter
125 ml all-purpose flour
550 ml milk
375 g ricotta
1 large egg
150 g crumbled Feta
170 g grated Gruyère cheese
400 g spinach lasagna noodles
150 g grated mozzarella
125 g grated parmesan

Preparation
Preheat oven to 180°C.
Soak porcini mushrooms in lukewarm water for 20 min.
Drain and reserve broth in a bowl.
Melt butter in a large heavy-bottomed saucepan until it froths.
Add all mushrooms, cook while stirring, until mushrooms are tender.
Remove from heat, stir in tarragon, parsley, add salt and pepper.
Transfer to a bowl and set aside.
Prepare a béchamel sauce in the same pan.
Cook shallots 1 min. in butter over medium heat.
Add flour and continue cooking for 2 min while stirring.
Whisk and slowly add milk and broth.
Add ½ tsp. salt and continue whisking until the sauce boils.
Simmer and stir until sauce thickens.
Remove from heat.
In a bowl, combine ricotta and egg.
Stir in 3 tbsp. béchamel and feta.
Add Gruyère cheese to the rest of the béchamel sauce in the pan and stir well.
Cook pasta accourding to manufacturer instructions.
To prevent it from sticking, leave to soak in cold water.
Remove and drain.
Pour 1/5 th of Gruyère sauce in a baking dish about 25 x 35 cm and cover with pasta.
Spread a quarter of ricotta mixture.
Sprinkle a quarter of the mushrooms and mozzarella.
Do this for three layers, finishing with a layer of dough covered with Gruyère sauce.
Sprinkle with Parmesan and cover with aluminum foil without touching sauce; bake in oven until the sauce is bubbling on the sides (about 40 min).
Remove aluminum foil and continue cooking for 10 min.
Remove from oven and let stand before serving.