Chicken and Leek Gratin with Gruyère

Preheat your oven to 375°F (190°C). Lightly grease an 8x8 inch baking dish.

Melt 2 tablespoons of butter in a large skillet over medium heat. Add the sliced leeks and cook, stirring occasionally, until softened, about 5-7 minutes. Remove the leeks from the skillet and set aside.

In the same skillet, melt the remaining 2 tablespoons of butter over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly, to create a roux.

Gradually whisk in the milk until the sauce is smooth and thickened, about 3-5 minutes. Stir in the salt, pepper, and nutmeg.

Add the cooked chicken and sautéed leeks to the sauce, stirring to combine everything evenly. Pour the mixture into the prepared baking dish.

Sprinkle the shredded Gruyère cheese evenly over the top of the chicken and leek mixture.

Bake for 25-30 minutes, or until the gratin is bubbly and the cheese is golden brown. Let it rest for 5 minutes before serving.