Preparation Heat oil in heavy large skillet over medium heat. Add onions and garlic. Sauté until onions are tender, about 8 minutes. Add mushrooms and bell peppers. Sauté until tender, about 20 minutes. (Can be prepared 8 hours ahead. Cover and refrigerate. Rewarm before continuing.) Cook fettuccine in large pot of boiling salted water until just tender but still firm to bite. Drain well; return pasta to pot. Meanwhile, add 1 1/4 cups whipping cream and cheese to mushroom mixture. Simmer gently over medium heat until cheese melts, stirring occasionally, about 4 minutes. Stir in chives, parsley and basil. Add sauce to pasta; toss to coat. Season pasta to taste with salt and pepper. Transfer to bowl and serve.
Preparation Heat oil in heavy large skillet over medium heat. Add onions and garlic. Sauté until onions are tender, about 8 minutes. Add mushrooms and bell peppers. Sauté until tender, about 20 minutes. (Can be prepared 8 hours ahead. Cover and refrigerate. Rewarm before continuing.) Cook fettuccine in large pot of boiling salted water until just tender but still firm to bite. Drain well; return pasta to pot. Meanwhile, add 1 1/4 cups whipping cream and cheese to mushroom mixture. Simmer gently over medium heat until cheese melts, stirring occasionally, about 4 minutes. Stir in chives, parsley and basil. Add sauce to pasta; toss to coat. Season pasta to taste with salt and pepper. Transfer to bowl and serve.