-5-6 baking potatoes, peeled and thinly sliced
-1/2 cup finely grated onion
-1 3/4 cups milk
-2 tbsp flour
-2 tbsp butter
-1 tsp salt
-1/2 tsp pepper
-1 cup grated cheddar cheese
Peel and thinly slice potatoes into a large bowl. Cover with cold water and allow to sit for 10 minutes. Drain well. (this gets rid of some of the starch in the potatoes) Add the grated onion and cheese and stir to combine.
Put potato mixture into a well greased casserole or 9x13 pan. In a small sauce pan (or microwave) melt butter. Stir in flour, salt and pepper. Add milk all at once and cook, stirring constantly until it bubbles and begins to thicken.
Pour hot milk mixture over potatoes. The milk should almost cover the potatoes. If you need add a little extra milk.
Bake covered in 350º oven for 40 minutes. Uncover and bake for 15-20 minutes longer or until potatoes are tender.