Cook spaghetti noodles according to package directions.

Preheat oven to 375 degrees

Drain mushrooms thoroughly into measuring cup; measuring the liquid. Add enough water (or chicken broth) to the liquid to make one half cup. Add the half-and-half.

Melt butter in a pan. Add flour, salt, and pepper. Stir to a smooth paste.

Gradually add broth mixture and cook, stirring constantly, until mixture thickens and comes to a boil.

Add chicken and mushrooms. Heat through.

Place the spaghetti in a 2 quart casserole dish. Spoon the chicken mixture over the spaghetti. Sprinkle with grated cheese.

Bake in a moderate oven at 375 degrees for approximately 15 minutes, or until lightly browned.

Note from Mary: I almost always use water instead of chicken broth. I also usually double the entire recipe. If you double it, use a 9x13 casserole dish. This dish can be frozen after assembling it completely.