1. Clean the mushrooms under running water.
2. Remove the stems and slice them. Put them in a sauté pan with ½ glass of lemon juice.
3. Chop the onion and add it to the mushrooms. Cover and cook until the water evaporates.
4. Add the heavy cream, salt, and pepper and mix
5. Place the cod fillets on top, then cover. Cook for about 10 minutes.
6. Meanwhile, cook the tagliatelle in a large pot of salted boiling water. Drain them quickly under running water.
7. Place a cod fillet on each plate. Arrange the pasta on the side and drizzle with mushroom sauce.
8. Garnish with chives and halved cherry tomatoes. Serve immediately.