Brush off any dirt from the mushrooms with a pastry brush or a tea towel. Slice the mushrooms thinly, but tear any larger mushrooms, like girolles, chanterelles. and blewits in half. Put the olive oil in a very hot frying pan, and add the mushrooms. Let them fry fast, tossing once or twice, then add the garlic and chile with a pinch of salt (it is very important to season mushrooms slightly, as it really brings out the flavor). Continue to fry fast for 4 to 5 minutes, tossing regularly. Then turn the heat off and squeeze in the lemon juice. Toss and season, to taste.
Meanwhile, cook the pasta in boiling, salted water until al dente. Drain and add to the mushrooms, with the Parmesan, parsley, and butter. Toss gently, coating the pasta with the mushrooms and their flavor. Serve, scraping out all of the last bits of mushroom from the pan, and sprinkle with a little extra parsley and Parmesan.