Fry the mushrooms in a large dry frying pan, stirring until the liquid evaporates. Then add a large piece of butter, garlic, leek and fry, stirring, until appetizing color. Sprinkle the pan with flour and continue frying for another minute.
Add thyme, cream cheese and sour cream and let it simmer a little.
Then mix it all with pasta, green peas and half of the cheese. Add salt and pepper to taste.