scalloped potatoes

Ingredients

1/2 onion, chopped
4 tbsp butter
4 tbsp flour
1/2 tsp salt
1/4 tsp pepper
2 cups milk
1/2 cup half and half
6 cups potatoes, peeled and sliced thinly
2 cups shredded cheddar cheese

Instructions
Use a large pot. Saute chopped onions in butter till soft but not browned.
In a small bowl, combine flour, salt and pepper.
Stir flour mixture into onion mixture, add milk and half and half.
Stir and cook over medium heat till mixture begins to thicken (about 3 minutes).
Turn off heat.
Add 1 1/2 cups cheese to the sauce and stir till melted and smooth.
Add sliced potatoes and stir well to combine.
Pour mixture into a 9x13 casserole dish sprayed with no stick spray.
Cover with foil and bake at 350 for 35 minutes.
Remove foil, sprinkle reserved cheese over top and return to oven to bake another 30 minutes until potatoes are soft, cheese is melted and edges begin to brown.
Let stand a few minutes before serving to allow sauce to thicken.