This has become one of my go-to potato dishes. I found it on the Weight Watchers site. About 5 points a serving. Quick and easy to make. The butter and flour is the classic combination to thicken the milk. The onions nicely get coated and this helps to prevent lumps from forming.
Preheat the oven to 375 (F).
Coast a 2 quart baking dish with cooking spray.
Melt butter in a large pot over medium heat. Add the sliced onion and cook, stirring as needed, until the onion starts to brown. About five (5) minutes.
Stir in the flour, stir until the onions are nicely coated with the butter and flour.
Slowly add in the milk, stirring so as no lumps form.
Add the potatoes, stir to mix. Bring the mixture to a boil. Add in 3/4 of the shredded cheddar cheese. Add slat and pepper.
Pour the mixture into the prepared baking dish. Bake for one hour, uncovered.
Then cover the potatoes and bake for another 20 minutes until tender.
Turn to over to broil. Add the remaining cheese. Broil about six inches from the heat for about 1-=2 minutes.
Allow to cool for five minutes. Cut into eight pieces. Serve.