Chicken and Artichoke Casserole

1/2 lb. fresh sliced mushrooms
2 T. butter
2 can (14 oz) chicken broth
4 chicken breasts
1 can (14 oz) artichoke hearts, drained
1/2 c. butter or margarine
1/2 c. flour
124 t. salt
1/4 t. pepper
1 1/2 c. light cream (half and half)
1 c. Parmesan cheese
1t. dried rosemary, crushed

Saute mushrooms in butter until golden brown.  Set aside.  Put chicken breasts in simmering chicken broth in a single layer.  Cover.  Cook 20 minutes.  Remove from broth (Save 3/4 broth).  Cool, skin and bone chicken.  Arrange chicken slightly overlapping in 8x12 casserole.  Top with artichoke hearts.  Set aside.  Melt 1/2 c. butter.  Stir in flour, salt and pepper until smooth.  Gradually stir in 1 1/2 c. chicken broth and light cream.  Cook and stir as mixture boils and thickens.  Blend in Parmesan cheese and rosemary.  Pour over artichokes, covering them.  Sprinkle mushrooms down center.  Bake at 325 degrees for 30 minutes.  You can assemble casserole ahead of time, cover and refrigerate.  Bake 10 minutes longer.  Serve with angel hair pasta. (Has been edited to how I usually make it.)