Cheesy Egg Casserole

Ingredients

• 1/2 c. butter or margarine
• 1/2 c. all-purpose flour
• 4 c. milk
• 1 tsp. salt
• 1/2 tsp. pepper
• 6 hard-boiled eggs, separated
• 3 Tbsp. butter or margarine
• 2 c. (8 oz.) shredded American cheese
• 1 small onion, chopped
• 2 (4 1/2 oz.) jars sliced mushrooms, drained
• 1 Tbsp. chopped parsley
• 1 (4 oz.) jar diced pimiento, drained
• 1/2 tsp. celery salt
• 1 Tbsp. sherry
• toast points or English muffins