Colorful Chicken Casserole

1 cup chopped green pepper
1 cup chopped celery
3/4 cup chopped onion
2 Tbsp butter or margarine
1 cup chicken broth
1 cup frozen peas
1 cup frozen corn
1 tsp salt, optional
1/4 tsp pepper
3 cup cubed cooked chicken
1 pkg(7oz) elbow macaroni, cooked and drained
1 jar(4-1/2oz) sliced mushrooms, drained
1 cup(4oz) shredded cheddar cheese

In large skillet, saute green pepper, celery and onion in butter until tender. Add broth, peas, corn, salt and pepper; heat through. Stir in chicken and macaroni. Divide between two greased 8-in. square baking pans. Top w/mushroom and cheese. Cover and freeze one casserole (up to 3 months). Cover the other one and bake 350 for 30 min; uncover and bake 10 min longer. To use frozen casserole: cover and bake at 350 for 35 min; uncover and bake 15 min longer.