Spaghetti "Au Gratin"
["9 oz. spaghetti", "1 medium onion, chopped", "2 heaping Tbsp. butter", "2 level Tbsp. flour or cornstarch", "salt", "pepper", "dash of powdered mustard (optional)", "2 1/2 c. milk", "7 oz. Parmesan cheese", "1 c. peas, cooked (optional)", "1/2 c. fresh bread crumbs", "2 Tbsp. melted butter"]
["Prepare spaghetti according to package directions.", "Drain and set aside.", "Saute onion with butter until soft.", "Add flour.", "Cook and stir for 1 minute.", "Gradually add 2 1/2 cups milk.", "Cook, stirring constantly, until sauce thickens and bubbles for 1 minute.", "Stir in salt, pepper and mustard.", "Remove from heat and add 3/4 of the Parmesan cheese."]
["spaghetti", "onion", "butter", "level", "salt", "pepper", "powdered mustard", "milk", "Parmesan cheese", "peas", "bread crumbs", "butter"]