3 tbsp. butter
2 tbsp. flour
1 tsp. salt
1/4 tsp. pepper
2 c. milk
3 1/2 to 4 c. thinly sliced potatoes (about 3 medium)
2 tbsp. minced onion

Place butter in 2 quart casserole dish. Microwave on high 1/2 minute or until melted. Blend in flour, salt and pepper. Gradually stir in milk. Microwave on high 8 to 10 minutes, stirring every 4 minutes. Add potatoes and onion, making sure potatoes are covered with sauce. Microwave 17 to 19 minutes on high. Let stand 5 minutes before serving.