Au Gratin Potatoes

Course Side Dish

Cuisine American, Southern

Keyword au-gratin-potatoes, best-au-gratin-potatoes-recipe, southern-au-gratin-potatoes

Prep Time 25

Cook Time 1

Stand time 10

Total Time 1 35

Servings servings (may vary)

Calories 328kcal

Preheat oven to 375°F. Butter an 11x8-inch (2.5 quart baking dish) or similar size baking dish with 1 Tablespoon of butter. Set aside.
Thoroughly clean potatoes and using a mandolin slice 1/8 inch slices.
Sauce: In a heavy bottomed saucepan, melt butter over medium heat. Add onion, cooking for 1-2 minutes or just until softened. Add garlic, cook for 1 minute. Add flour, stir until butter is absorbed.
To the flour add salt, black pepper, ground mustard and nutmeg. Gradually whisk in milk. Add thyme. Bring to a light bubble then immediately lower the heat to simmer for 3-5 minutes, stirring occasionally.
Remove from heat. Add 1 cup Gruyere and 1/4 Parmesan cheese to sauce, Mix until melted.
Assemble: Layer 1/2 potato slices fanned and overlapping in greased baking dish. Spread 1/2 sauce evenly over potatoes.
Repeat remaining potatoes, spread with sauce. Sprinkle top with remaining Gruyere and sprinkle with 3 Tablespoons of Parmesan.
Cover with foil and bake for 50-60 minutes. Uncover, increase oven temperature to 400 °F. Bake for another 20 minutes or until the top is golden brown and the potatoes are fork tender.
Let stand 5-10 minutes of the sauce to thicken then serve garnished with fresh thyme.

- Cheese: I use Gruyere cheese in this recipe. You could adapt using another variety of cheese such as sharp cheddar cheese, gouda cheese or colby jack cheese, according to your taste or what you have on hand. For special occasions, Gruyere is the way to go.
- Butter: You can use unsalted butter for the sauce. Taste and add more salt to your taste to accommodate.
- Milk: Whole milk works very well for the sauce. If you really want to go for the gold, use half and half or heavy cream.