Look, we're frying potatoes. We get “fried potatoes”, with one “n”, order. Another case: we were frying potatoes and decided to add mushrooms to them for taste. then we have a dependent word and it turns out “potatoes fried with mushrooms”, with two “n”s, but everything seems to be logical. or maybe there was a time when we fried potatoes, put them on a plate and decided to add mushrooms. it turns out “fried potatoes with mushrooms”, and here again there is one “n”. you see, it all depends on at what point you added the mushrooms