Scalloped Potatoes by Gordon Ramsay is an excellent potato casserole, with soft potatoes enfolded in a creamy onion sauce that turns brown with careful baking. In just 1 hour and 20 minutes, you can impress everyone with your mastery of the kitchen.
Turn the oven temperature up to 350 degrees Fahrenheit.
Sauce
Melt the butter, onion, and garlic over medium-low heat to make the sauce.
Cook for about 3 minutes, or until the onion is tender. Mix in flour and cook for 1 to 2 minutes.
Turn down the heat. Mix the milk and the broth together. Slowly add it while whisking so that it thickens.
Add more liquid, a little at a time, while whisking constantly, because the mixture would get extremely thick otherwise.
Add the liquid gradually, whisking constantly, and bring to a boil over medium heat. Add salt and pepper to taste and allow to boil for 1 minute.
Assembly
Grease a 9x13-inch baking dish. Layer the bottom with ⅓ of the potatoes and season with salt and pepper.
Cover with a third of the cream sauce.
Repeat the layers, finishing with the cream sauce. Bake for 45 minutes covered.
Remove the lid and bake for another 35 to 45 minutes, or until the potatoes are golden and soft. Allow the top to broil for three to four minutes.
Let it sit for 15 minutes before serving.
Notes
You can speed up your work considerably by using a mandoline.
If you want to make a smooth sauce, start with a roux. Cooking oil (in this case, butter) and flour before adding liquid produces a sauce known as a roux.
To turn these potatoes into Potatoes Au Gratin, take the sauce off the heat and toss in 1 1/2 to 2 cups of cheese (cheddar or gruyere work well).
Layer the potatoes while seasoning each layer with salt and pepper.
If you cover it with foil before baking, the steam will help the potatoes cook more quickly.