Invisible Au Gratin Potatoes

Christmas has officially vomited all over the house, and some of it has gotten on the animals, too.

I'm about to post a recipe, and you may notice the lack of accompanying photo. That is because 1) one of us forgot to take the foil off to let it brown nicely, so it was ugly and unappetizing-looking; and 2) because we almost ate it all before I had a chance to decide I wasn't taking a photo.

So make this. Just, for the love of Mike, remember to take the foil off.

Cheesy Au Gratin Potatoes

Cheese sauce:
3 tbsp. butter
3 tbsp. flour
1 1/2 cups milk
1 1/2 cups half and half
A few good handfuls of cheese (maybe 2 1/2 cups? as much as you want. I doubt you could use too much.)
Salt, pepper, and hot sauce to taste

4-6 russet potatoes, peeled and sliced thinly

1 medium onion, sliced thinly (use less if it's a super-funky one)

Salt and pepper

To make the cheese sauce: Melt the butter and whisk in the flour; cook for a minute. Add milk and half and half; whisk and stir over high heat until thickened. Remove from heat and whisk in cheese. Season with salt, pepper, and hot sauce; set aside.

Spray a 1-quart baking dish with nonstick spray. Lay half of the potato slices in the bottom, and top with half of the onion. Sprinkle with salt and pepper, then repeat with remaining potato and onion. Top with cheese sauce.

Cover tightly with foil and bake at 400 degrees for 1 hour. REMOVE FOIL, everyone, and bake for another 30 minutes.