Scalloped Potatoes

Preheat oven to 375℉, grease a 9x13 baking dish with nonstick cooking spray; set aside.
In a medium saucepan over medium heat, melt the butter, add flour, whisking until fully incorporated. Cook for 2-3 minutes, until slightly golden. Add the minced garlic and cook for an additional 30-45 seconds.
5 tablespoons unsalted butter, 5 tablespoons all-purpose flour, 2 garlic cloves
Add the chicken broth, whisking to incorporate. Add half and half slowly, whisking constantly. Continue to cook, whisk often, until the mixture has thickened and just begins to bubble, about 4-5 minutes. Do NOT bring to a rolling boil.
½ cup chicken broth, 2 cups milk
Remove the pan from the heat and stir in cheese a handful at a time until melted. Stir in the salt, pepper, and thyme; set aside.
2 cups shredded cheese, 1 teaspoon salt, ½ teaspoon black pepper, 1 teaspoon fresh thyme
Using a kitchen mandolin or sharp knife, peel and slice potatoes into ¼ inch rounds.
3 pounds potatoes
Layer half the sliced potatoes in the baking dish. Add onions, then pour on half the cheese sauce. Repeat with the remaining potatoes and sauce.
½ cup onion
Cover tightly with foil and bake for 70-80 minutes, or until potatoes are tender. Uncover and bake for 15 additional minutes, until the top is golden and bubbling. Let rest for 10 minutes before serving. Garnish with parsley if desired.
fresh parsley