Ultimate Creamy au Gratin Potatoes
Introduction
If you’re looking for a show-stopping side that’s pure comfort in every bite, these Ultimate Creamy au Gratin Potatoes are your answer. Thin slices of tender potato nestled in a luxuriously creamy, garlicky cheese sauce and finished with a golden, bubbling crust—this is the dish that turns weeknight dinners into something special and makes holidays unforgettable. It’s indulgent, satisfying, and surprisingly straightforward to make.
Ingredients
- 2 lbs Yukon Gold potatoes (about 4-5 medium), peeled
- 3 tbsp unsalted butter
- 3 tbsp all-purpose flour
- 2 cups whole milk
- 1 cup heavy cream
- 2 cloves garlic, minced
- 1 tsp Dijon mustard
- 2 cups shredded Gruyère cheese (about 8 oz), divided
- 1/2 cup shredded sharp cheddar cheese
- 1 tsp salt
- 1/2 tsp black pepper
- 1/4 tsp ground nutmeg
Instructions
- Prep: Preheat oven to 400°F (200°C). Grease a 9x13-inch baking dish with butter or non-stick spray.
- Slice Potatoes: Using a sharp knife or mandoline, thinly slice potatoes to about 1/8-inch thickness. Place slices in a large bowl of cold water to prevent browning.
- Make the Sauce: In a medium saucepan, melt butter over medium heat. Add flour and whisk constantly for about 1 minute to create a roux.
- Add Liquids: Gradually pour in milk and heavy cream, whisking continuously until smooth. Add minced garlic and Dijon mustard. Bring to a simmer, stirring frequently, until sauce thickens enough to coat the back of a spoon (about 5-7 minutes).
- Add Cheese: Remove saucepan from heat. Stir in 1½ cups Gruyère and all the cheddar cheese until melted and smooth. Season with salt, pepper, and nutmeg.
- Layer: Drain potato slices and pat them dry with a kitchen towel. Arrange half of the potatoes in the prepared baking dish, overlapping slightly. Pour half of the cheese sauce evenly over the first layer. Repeat with remaining potatoes and sauce.
- Top & Bake: Sprinkle the remaining ½ cup Gruyère over the top. Cover the dish with aluminum foil and bake for 40 minutes.
- Brown the Top: Uncover and continue baking for another 20-25 minutes, or until the top is golden brown and bubbly, and a knife easily pierces the potatoes.
- Rest & Serve: Let the dish rest for 10 minutes before serving to allow the sauce to set slightly. Garnish with chopped fresh chives or parsley, if desired.
Pro Tips & Notes
- Choose Your Potatoes: Yukon Golds are ideal for their creamy texture and buttery flavor. Russet potatoes also work well, but may result in a slightly fluffier layer.
- Slice Evenly: A mandoline ensures uniformly thin slices, which is key to even cooking and a cohesive dish. Watch your fingers!
- Don’t Rush the Sauce: Let the roux cook for a full minute to get rid of the raw flour taste, and add the milk gradually to prevent lumps. A smooth sauce is the goal.
- Let It Rest: Resisting the urge to dig in right away is tough, but letting the gratin rest for 10 minutes allows the sauce to thicken properly so your servings hold their shape.
- Make-Ahead Friendly: You can assemble the gratin a day ahead. Cover tightly with plastic wrap and refrigerate. Let it sit at room temperature for 30 minutes before baking as directed.
Nutrition Facts (per serving)
- Calories: 520
- Protein: 18g
- Carbohydrates: 45g
- Fat: 30g
- Saturated Fat: 18g
- Cholesterol: 95mg
- Sodium: 780mg
- Fiber: 4g
- Sugar: 8g
Frequently Asked Questions
- Q: Can I prepare this dish in advance? A: Yes, assemble the gratin up to a day ahead. Cover and refrigerate. Let it come to room temperature for about 30 minutes before baking. You may need to add 5-10 minutes to the covered baking time.
- Q: What cheese can I substitute for Gruyère? A: If Gruyère is unavailable, Swiss cheese or a combination of Swiss and Fontina make excellent substitutes that still deliver great flavor and meltability.
- Q: How can I make it less rich? A: You can replace the heavy cream with an additional 1 cup of whole milk for a slightly lighter version. The result will be less decadent but still creamy and delicious.
- Q: Why are my potatoes still firm? A: This usually happens if the potatoes are sliced too thickly or the oven temperature is too low. Ensure your slices are thin (under 1/4 inch) and verify your oven temperature with a thermometer.