Slice mushrooms finely, dice onion and crush garlic.
Warm up olive oil in a saucepan and add a pinch of dried oregano, one onion and the crushed garlic clove and cook until onion is translucent.
Put in mushrooms, add salt and pepper to taste. Let the mushrooms cook until soft, do not remove the water that has released from the mushrooms.
Boil tagliatelle in separate saucepan.
Put single cream into the mushrooms to form a sauce.
Drain the tagliatelle and stir into the mushroom sauce. Finish with grated Parmesan.