Noodles with Creamy Chicken Mushroom Sauce

2 Tablespoons butter or margerine
2 green onions or 1 medium onion chopped fine
1 cup mushrooms, thinly sliced

1 1/2 cups chicken stock

1 1/2 cups pasta noodles

1/2 cup half and half or milk or evaporated skim milk
4 teaspoons cornstarch

2 cups diced cooked chicken
2 teaspoons Dijon mustard
1/4 teaspoon salt and 1/4 teaspoon pepper

1.4 cup grated Parmesan (optional)

Melt butter in 10 inch nonstick skillet over moderate heat.
Add green onions and saute, stirring for about 1 minute.
Add mushrooms and saute, stirring occasionally for 3 minutes, or 
until limp.

Pour in stock and bring to a boil. Adjust heat so mixture bubbles gently.
Simmer, uncovered, stirring occasionally for 5 minutes.

Cook noodles.

Blend half and half with the cornstarch in a small bowl.

Whisk cornstarch mixture into skillet and cook, stirring constantly for 2 to 3 
minutes or until thickened.
Mix in chicken, muistard, salt and pepper.
Simmer, uncovered, stirring occasionally, for 5 minutes.

Drain pasta and transfer to large serving bowl.  
Add skillet mixture and toss well.
Serve with cheese if desired.