Broccoli With Cheese
["1 small onion, chopped", "4 Tbsp. butter or margarine", "1/4 c. all-purpose flour", "2 c. milk", "salt and pepper to taste", "1 egg yolk, beaten", "1 c. grated Parmesan cheese", "2 lb. cooked broccoli spears", "1/2 c. dry bread crumbs", "2 Tbsp. butter or margarine, melted"]
["Preheat oven to 400\u00b0.", "Spray 13 x 9 x 2 baking pan with nonstick cooking spray.", "Cook onion in 4 tablespoons butter in a skillet until tender."]
["onion", "butter", "all-purpose", "milk", "salt", "egg yolk", "Parmesan cheese", "broccoli spears", "bread crumbs", "butter"]