Season with salt and pepper to taste.
Place the pasta in the boiling water and cook for 30 seconds to 1 minute, or until al dente.
Test frequently; do not overcook.
Drain well.
Toss the hot pasta in the mushroom sauce and serve immediately.
CHICKEN STOCK: Place chicken bones & trimmings w/2-1/2 qts. water in stockpot.
Bring slowly to boil, simmer about 30 min.
Add celery, carrot, onion, bay leaf, peppercorns, thyme, & season to taste w/salt & pepper.
Simmer 1-1/2 to 2 hrs. longer, or until reduced to 1 qt.
Skim any scum that rises to the surface.
Remove chicken bones, trimmings, and bay leaf.
Strain stock through fine sieve, pushing vegetables through for extra flavoring.
Cool, then refrigerate until ready to use.