Creamy Au Gratin Potatoes

A top down shot of au gratin potatoes in a baking dish with blue handles next to a grey cloth.

5 from 1 vote

These Creamy Au Gratin Potatoes are a comforting and classic side dish choice. Thinly sliced Yukon gold potatoes and diced onions are baked with a rich and creamy cheese sauce until tender and golden brown.

Prep Time20

Cook Time1 20

Resting Time5

Total Time1 45

Course: Side Dish

Cuisine: American, French

Servings:

Calories: 329kcal

Author: Valerie Brunmeier

Ingredients

3 pounds Yukon Gold potatoes peeled or unpeeled (see Notes below)
½ teaspoon Lawry's Seasoned Salt
1 cup diced sweet yellow onion
minced fresh herbs like parsley or thyme leaves optional garnish

Cheesy Bechamel Sauce

3 tablespoons butter
3 tablespoons flour
2 cups milk warmed in microwave for 1 minute
1 teaspoon Dijon mustard
1 teaspoon salt
½ teaspoon garlic powder
¼ teaspoon freshly ground black pepper
1 ½ cup shredded cheddar cheese
½ cup shredded Parmesan cheese

Instructions

Preheat oven to 400 degrees F. Coat a 13- x 9-inch baking dish with nonstick cooking spray.
Thinly slice the potatoes about ⅛-inch thick with a mandolin or sharp knife and set aside.

Make the Bechamel Cheese Sauce

Add the butter to a large saucepan and place it over LOW heat. Allow the butter to melt, being careful it does not brown. Add the flour and cook, whisking, for about 3 to 4 minutes. Gradually whisk in the warm milk, a little at a time, whisking as you add it to smooth out any lumps. Add the Dijon and continue to cook, whisking, for several minutes or until completely smooth and nicely thickened. You can increase the heat a little to help it thicken if needed, but don’t let it boil. Remove from the heat. Stir the salt and garlic powder into the bechamel. Add the cheddar and Parmesan cheese and stir until melted.

Assemble the Au Gratin Potatoes

Sprinkle half of the onions over the bottom of the prepared baking dish and drizzle with a little of the cheese sauce (not a lot - about ¼ to ⅓ of the sauce). Place the sliced potatoes over the top in rows and sprinkle with the remaining onion and the seasoned salt. Pour the remaining cheese sauce evenly over the top, spreading it out with the back of the spoon so that all of the potatoes are covered.

Bake

Spray the underside of a large piece of foil with nonstick cooking spray and cover the dish. Bake for 50 minutes. Remove the foil and continue to bake for an additional 30 to 35 minutes or until nicely browned and bubbly and the potatoes are fork tender. Remove from the oven and let rest for 5 to 10 minutes. Garnish with fresh herbs, if desired, before serving.

Notes

To Peel or Not to Peel

If using thin-skinned Yukon Gold potatoes, there is no need to peel them first. You can peel them if you'd like, but they can actually help the slices retain their shape when baked. Once the potatoes are thinly sliced, the skins are just barely visible but add a nice rustic quality.

Variations

Cheese - There are many varieties of cheese that are delicious in Au Gratin potatoes. Try substituting part of the sharp cheddar with Gruyere or Monterey Jack cheese. Other good melting cheeses like Havarti or Gouda would also be delicious. Be sure to use freshly shredded cheese which melts much better than pre-shredded bagged cheese.
Fresh herbs - Garnish the Au Gratin potatoes with fresh thyme leaves, minced parsley, or chives before serving.

Make-Ahead Tips

You can assemble the dish up to 24 hours in advance. Once the potatoes have been covered with the cheese sauce, cover the dish with aluminum foil as directed and transfer it to the refrigerator. Allow the dish to sit on the kitchen counter for 30 to 60 minutes before baking to take the chill off.

Nutrition