Roll out pasta to No. 4 setting, roughly 1/8th inch thick. Cut pasta sheets into 4 inch long pieces and fold each in half. Cut roll into strips 1/2 inch thick. Take each piece between hands and roll back and forth several times to form a twisted piece. Set aside.
Bring 6 quarts water to boil and add 2 tablespoons salt.
In a 12 to 14 inch sauce pan, heat olive oil, and saute onion and celery over medium high heat until soft, about 8 to 10 minutes. Add mushrooms and cook until sweated, about 8 to 10 minutes. Add tomato sauce and bring to a boil. Meanwhile, drop pasta into boiling water and cook 1 minute until soft. Drain well and place in pan with mushrooms. Toss until well coated. Add parsley, transfer to warm platter and serve.