Toni’s Scalloped Potatoes

6 potatoes sliced very thin
1/2 – 1 cup yellow onion, chopped

3 cups milk (not skim — 2 percent OK)
3 tablespoons butter
2 tablespoons flour
1 teaspoon salt
dash of pepper

For Sauce:
Melt butter
Remove from heat and add flour slowly to form a paste without scorching
Add milk, salt and pepper

Place half of sliced potatoes in casserole
Add layer of onions, salt and pepper
Add half of sauce

Bake at 350 about an hour and a half