Cheesy Potatoes Au Gratin
These cheesy potatoes au gratin are made with thinly sliced Yukon gold potatoes baked in a rich, three-cheese cream sauce with cheddar, smoked Gouda, and Boursin. They’re ultra-creamy, golden and bubbly on top, and perfect for holidays, Sunday dinners, or any time you’re craving cozy comfort food.
Servings 8
Ingredients
For the Cheese Sauce
- 4 tbsp Salted Butter
- 1 Yellow Onion, Diced
- 4-5 Garlic Cloves, minced
- 1/4 Cup All Purpose Flour
- 4 Cups Half and Half, room temperature
- 1 tbsp Herbs De Provence
- 1 tsp Dried Mustard Powder
- 1 tsp Salt plus more for the potatoes when layering
- 1/2 tsp Black Pepper
- 1 Cup Freshly Shredded Sharp Cheddar Cheese
- 1 Cup Freshly Shredded Smoked Gouda Cheese
- 1 (5.3 oz) Boursin Garlic and Herb Cheese
For the Potatoes and Topping
- Butter for greasing the baking dish, or cooking spray works too
- 3 lbs Yukon Gold Potatoes, thinly sliced mandolin recommended
- 1 Cup Freshly Shredded Sharp Cheddar Cheese
- 1 Cup Freshly Shredded Gouda Cheese
Instructions
- Preheat your oven to 375°F. Generously butter an 11-inch pie plate or similar baking dish. Place the dish on a baking sheet or drip pan to catch any overflow.
- In a large skillet over medium heat, melt the 4 tablespoons of butter. Add the diced onion and cook for about 5 minutes, until softened. Stir in the minced garlic and cook for another minute, until fragrant.
- Whisk in the 1/4 cup flour and cook for 1–2 minutes, stirring often, to cook out the raw flour taste.
- Slowly pour in the 4 cups of half-and-half, about 1 cup at a time, whisking constantly. Continue cooking and whisking until the sauce thickens and is smooth and creamy.
- Stir in the herbs de Provence, dried mustard, black pepper, and 1 teaspoon salt. Reduce the heat to low and add 1 cup cheddar, 1 cup smoked Gouda, and the Boursin, stirring until all the cheese is melted and the sauce is smooth.
- Using a mandolin, thinly slice the 3 pounds of Yukon gold potatoes. Arrange about one-third of the slices in an even layer in the buttered dish. Lightly sprinkle with salt, then pour about one-third of the cheese sauce over the top. Repeat with two more layers of potatoes, salt, and sauce, ending with sauce.
- Cover the dish tightly with foil and bake at 375°F for about 1 hour, or until the potatoes are mostly tender when pierced with a knife.
- Remove the foil and sprinkle the top with the remaining 1 cup cheddar and 1 cup smoked Gouda. Return to the oven and bake uncovered for 20–30 minutes, or until the top is golden brown, bubbly, and slightly crisp around the edges.
- Remove from the oven and let it rest for 10–15 minutes before serving, which allows the sauce to thicken and set.
Notes
- Salt each layer: For the best flavor, lightly salt each layer of potatoes as you build the dish. If you only season the sauce, the potatoes in the middle can taste a little flat. Salting the layers ensures every bite of your cheesy potatoes au gratin is well seasoned from top to bottom.
- Let it rest before serving: It’s tempting to dig in right away, but letting the potatoes rest for 10–15 minutes is important. The sauce thickens and sets as it cools slightly, so the potatoes slice and serve more cleanly and the texture stays nice and creamy instead of soupy.
- Dish size and drip pan: An 11-inch pie plate will hold this recipe, but it will be quite full and may bubble over a bit. Place it on a baking sheet or drip pan to keep your oven clean, or use a slightly larger baking dish if you prefer more wiggle room.
- Make-ahead: You can assemble the potatoes and cheese sauce in the dish, cover tightly with foil, and refrigerate for up to 1–2 days before baking. Let it sit at room temperature for about 20–30 minutes, then bake as directed (adding a little extra time if needed).
- Leftovers: Store leftovers in an airtight container in the fridge for 3–4 days. Reheat in the microwave or in a 325°F oven (covered with foil) until hot. If needed, add a splash of half-and-half before reheating to keep everything creamy.