Mushroom sauce ingredients:
10 g of dry king oyster mushrooms
2 tablespoons of olive oil
2 onions cut into thin slices
2 cloves of garlic, finely chopped
500 g of fresh chestnut mushrooms, cut into slices
1 bay leaf
2 sprigs of thyme
500 ml of quality tomato puree
200 g buffalo mozzarella (or bocconcini), sliced, drained on a paper towel
375 g of fresh lasagna pasta
1/2 cup (40 g) grated Parmesan cheese, plus extra for serving
Bechamel sauce ingredients:
1L (4 cups) of milk
1 onion, halved
1 bay leaf
1 sprig of thyme
50 g of unsalted butter
1/3 cup (50 g) plain flour
A pinch of nutmeg
Instructions:
1. Heat the oven to 180°C and grease a 30 cm baking dish.
2. Soak dried king oysters in 1/2 cup (125 ml) of boiling water for 10 minutes.
3. Meanwhile, heat the oil in a large frying pan over medium heat. Cook the onion, stirring, for 5-6 minutes or until softened. Add the garlic, chestnut mushrooms, bay leaf and thyme, then cook, stirring, for 2-3 minutes until the mushrooms begin to wilt and caramelize. Add the king oysters and soaking liquid, then cook for another 2 minutes until most of the liquid has evaporated. Mix in the passata and 1 cup (250 ml) of water and season well. Set it aside.
4. Meanwhile, for the béchamel, put the milk, halved onion, bay leaf and thyme in a pan over medium-high heat and heat just below the boiling point. Remove from the heat and leave for 15 minutes for the flavors to meld. Melt the butter in a pan over medium-low heat. Add the flour and mix for 2 minutes until the mixture is smooth and combined. Strain the milk through a sieve into a pitcher, then gradually stir into the butter mixture until smooth. Add nutmeg, season, and stir over low heat for 3-4 minutes until it thickens.
5. To assemble the lasagna, put half of the mushroom sauce into a baking dish over a layer of pasta sheets, spread one-third of the bechamel, then top with half of the mozzarella. Cover with the pasta sheets, then repeat with the remaining mushroom mixture, half of the remaining bechamel, and the remaining mozzarella and pasta. Finish with a final layer of béchamel, sprinkle with parmesan, then cover with baking paper and foil. Bake for 45 minutes, then uncover and bake for another 15 minutes until golden brown and cooked through. Rest for 10 minutes, then slice and serve with extra Parmesan cheese.
