Stir in the mushrooms and the remaining butter, then cover the pan with the lid and cook for about 10 minutes, stirring occasionally. Add the dried pasta and cook according to the packet instructions. Step 4When the pasta is almost cooked, stir the crème fraîche or soured cream into the mushroom mixture. Drain the pasta and add it to the mushroom mixture, then toss everything together gently. Step 5To serve, divide the pasta and sauce between two bowls, grate over the Comté and sprinkle with flat-leaf parsley.