Ham and Scalloped Potatoes

1. Heat oven to 350 degrees Fahrenheit.
2. Grease a 2 quart oven safe casserole dish.
3. Cut potatoes in enough thin slices to measure about 4 cups.
4. Melt 3 tablespoons of margarine in a 2 quart saucepan over medium heat.  Cook the onion in the margarine for about 2 minutes stirring occasionally, until tender.  Stir in flour, salt, and pepper.  Cook, stirring constantly, until smooth and bubbly.  Remove from heat.
5. Stir milk into sauce.  Heat to boiling, stirring constantly.  Boil and stir 1 minute. Stir in ham.  
6. Spread potatoes in a oven safe casserole dish.  Pour sauce over potatoes.  Dot with a 1 tablespoon margarine. 
7. Cover and bake for 30 minutes in the oven.  Uncover and bake 1 hour to 1 hour 10 minutes longer or until potatoes are tender. Let stand 5 to 10 minutes before serving. 

Recipe is from the "Betty Crocker Country Cooking" cookbook.