Easy Potatoes au Gratin

Ingredients

• 3 tbsp unsalted butter (plus more for greasing the dish)
• 1 yellow onion (small, finely chopped)
• 3 cloves garlic (minced)
• 3 tbsp all-purpose flour
• 2 cups whole milk
• 1 cup heavy cream
• 1 tsp fresh thyme (chopped, plus more for garnish)
• 1.5 tsp kosher salt
• 0.5 tsp black pepper
• 2 cups sharp cheddar cheese (shredded, divided)
• 1 cup Gruyère cheese (shredded, divided)
• 3 lb Russet potatoes (peeled and sliced into 1/8-inch thick rounds)

Steps

1. 1

   Preheat your oven to 375°F (190°C). Grease a 9x13 inch baking dish with butter.

2. 2

   In a large saucepan or Dutch oven, melt 3 tablespoons of butter over medium heat.

3. 3

   Add the chopped onion and sauté for about 5 minutes, or until softened and translucent.

4. 4

   Add the minced garlic and cook for 1 minute until fragrant.

5. 5

   Whisk in the flour and cook for 1-2 minutes to remove the raw flour taste, creating a roux.

6. 6

   Slowly whisk in the milk and heavy cream. Continue whisking until the mixture is smooth and begins to thicken, about 5 minutes.

7. 7

   Stir in the salt, pepper, and chopped thyme.

8. 8

   Remove the sauce from heat and stir in 1.5 cups of the cheddar cheese and 0.5 cups of the Gruyère cheese until melted and smooth.

9. 9

   Place half of the sliced potatoes in an even layer in the prepared baking dish.

10. 10

    Pour half of the cheese sauce over the first layer of potatoes.

11. 11

    Layer the remaining potatoes on top and pour the rest of the cheese sauce over them, spreading it evenly to cover.

12. 12

    Cover the dish tightly with aluminum foil and bake for 45 minutes.

13. 13

    Remove the foil and sprinkle the remaining 0.5 cup of cheddar and 0.5 cup of Gruyère over the top.

14. 14

    Bake uncovered for another 15-20 minutes, or until the potatoes are tender when pierced with a fork and the top is golden brown and bubbly.

15. 15

    Let the dish rest for 10 minutes before serving to allow the sauce to set. Garnish with additional fresh thyme if desired.

Notes

For the best texture, use a mandoline to ensure the potato slices are uniform in thickness. Russet potatoes are recommended for their starch content, which helps thicken the sauce, but Yukon Gold potatoes also work well for a creamier texture.

Nutrition per serving

• side dish
• potatoes
• cheesy
• baked
• comfort food
• holiday
• vegetarian