Scalloped Potatoes

Preheat oven to 350˚F, Thinly slice potatoes & onions. Get all the other shit out.
INGREDIENTS:
¼ cup butter
1 large onion diced
2 cloves garlic minced
¼ cup flour
2 cups milk
1 cup chicken broth
½ teaspoon salt
¼ teaspoon pepper
3 pounds white potatoes sliced about ⅛" thick
salt and pepper to taste

SAUCE: 
Melt butter, onion and garlic over medium low heat. Cook until onion is softened, about 3 minutes. Add flour and cook for 1-2 minutes. 
Reduce heat to low. Combine milk and broth. Add a small amount at a time while whisking and thickening.
Once all of the liquid has been added, bring to a boil over medium heat while continuing to whisk.  Stir in salt and pepper and let boil 1 minute.\
Add 1-1/2" cup grated cheese with the pot off the stove if you want to call this Au Gratin.

ASSEMBLE and BAKE:
Grease a 9"x13" baking dish. Place ⅓ of the potatoes in the bottom and season with salt and pepper. Pour ⅓ of the cream sauce sauce over top. 
Repeat layers ending with cream sauce. Cover and bake for 45 minutes.
Uncover and bake for an additional 35-45 minutes or until golden brown and potatoes are tender. Broil for 3-4 minutes to obtain a golden top.
Allow to rest for 15 minutes before serving.

SERVING NEXT DAY?
If serving next day, cook just 50-60 minutes (covered) then cool completely on the counter (leave them covered, the steam will help to finish cooking).
Cover well and refrigerate.
On the day of serving, remove from the fridge at least 30 minutes before baking. Bake uncovered about 35 minutes or until heated through.