Zesty California Walnut Penne

Heat oil in large, heavy skillet over medium heat. Add onion and mushrooms and sauté, stirring, 5 minutes. Add garlic and sauté, 1 minute. Add tomatoes breaking up with wooden spoon, herbs and walnuts. Cook, stirring, 10 to 15 minutes. If mixture thickens too much, add a little chicken stock or red wine. Meanwhile, in a large pot of boiling water, cook pasta, stirring, 8 to 10 minutes, just until tender but still firm to bite. Drain well; return pasta to pot. Pour walnut-tomato sauce over pasta and toss to coat. Sprinkle with Asiago cheese and season to taste with pepper. Serve on heated plates. Garnish with parsley.