Wash the mushrooms, drain them well, then slice them.
Finely chop the onion and garlic.
Sauté the onion and garlic in a pan with the olive oil.
Add the mushrooms once the onion becomes translucent.
Cook over medium heat until the mushrooms are almost tender.
Add a little water if the sauce looks too thick.
Add the shrimp and cook for about 10 minutes.
Add the sesame oil and oyster sauce, then season with salt and pepper to taste.
Add the cream just before serving and once the tagliatelle are cooked. Let it simmer for a few minutes until the sauce thickens.
Add the pesto and mix well.