Potatoes Au Gratin

Preheat the Oven - Set the oven rack to the middle position. Heat to 400ºF (200ºC).

Make the Cream Sauce - Melt the butter in a large skillet over medium-low heat. Add garlic and onions, and saute until fragrant, 2 minutes. Add flour, whisk to combine, stir and cook for 2 minutes. Gradually whisk in milk and cook until thickened over medium heat, 2 to 3 minutes. Turn off the heat and whisk in salt, pepper, and nutmeg.

Add the Cheeses - Add ½ cup gruyere and ½ cup sharp cheddar cheese, and stir to combine.

Assemble the Casserole - Grease the bottom and sides of an 8-inch square casserole dish. Layer half of the potatoes in overlapping rows in the dish. Spread half of the cheese sauce over the potatoes. Sprinkle ¼ cup gruyere and ¼ cup cheddar over the sauce. Layer the remaining potatoes, followed by the cheese sauce, and sprinkle with the remaining gruyere and cheddar cheese.

Bake - Cover with foil and place on a baking sheet. Bake for 30 minutes. Remove the foil and continue baking until the potatoes are tender and the cheese is browned and bubbly, 20 to 25 minutes.

To Serve - Transfer the casserole to cool on a wire rack for 10 to 15 minutes before serving. Garnish potatoes with chives.