Spaghetti "Au Gratin" - cooking recipe

Ingredients

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

Preparation

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.