Scalloped Potatoes Au Gratin with Onions

Indulge in the ultimate comfort food with this Scalloped Potatoes Au Gratin with Onions recipe, a rich and creamy classic that takes your taste buds to new heights. Thinly sliced russet potatoes and sweet, golden caramelized onions are layered with a velvety cheese sauce made from sharp cheddar, Parmesan, and a hint of fresh thyme, creating a heavenly combination of flavors. This dish is lovingly baked to golden-bubbly perfection, offering a crisp, cheesy crust atop fork-tender potatoes. Perfect for holidays, dinner parties, or a cozy family meal, this decadent side dish pairs beautifully with roasted meats or seasonal vegetables. Ready in about 90 minutes, it’s a showstopper that’s worth every bite.

Nutriscore Rating: 64/100

Prep Time:20 mins

Cook Time:75 mins

Total Time:95 mins

Servings: 6

Ingredients

• 6 medium Russet potatoes
• 1 large Yellow onion
• 4 tablespoons Unsalted butter
• 3 tablespoons All-purpose flour
• 2.5 cups Whole milk
• 0.5 cups Heavy cream
• 2 cups Shredded sharp cheddar cheese
• 0.5 cups Grated Parmesan cheese
• 3 cloves Garlic
• 1 teaspoon Fresh thyme
• 1.5 teaspoons Salt
• 0.5 teaspoons Black pepper
• 1 tablespoon Olive oil

Directions

Step 1

Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with butter or non-stick spray and set aside.

Step 2

Peel the potatoes and slice them thinly into 1/8-inch rounds. Use a mandoline slicer if available for consistent slices.

Step 3

Peel and slice the onion into thin rings. Set aside.

Step 4

In a large skillet over medium heat, heat the olive oil and sauté the onion rings until they are golden and caramelized, about 8-10 minutes. Stir occasionally to prevent burning. Set aside.

Step 5

In a medium saucepan, melt the butter over medium heat. Add the minced garlic and cook for about 1 minute until fragrant.

Step 6

Whisk in the flour and cook, stirring frequently, for 1-2 minutes to form a roux. Gradually add the milk while whisking continuously to prevent lumps.

Step 7

Stir in the heavy cream, salt, black pepper, and thyme. Bring the mixture to a simmer, stirring frequently, until it thickens slightly, about 3-4 minutes. Remove from heat.

Step 8

Stir in 1.5 cups of the shredded cheddar cheese and 1/4 cup of the Parmesan cheese until they melt completely into the sauce.

Step 9

Spread a thin layer of the cheese sauce on the bottom of the prepared baking dish. Arrange a single layer of potato slices over the sauce, slightly overlapping them.

Step 10

Sprinkle a small amount of the caramelized onions over the potatoes, then pour about 1/3 cup of cheese sauce on top. Spread to coat evenly.

Step 11

Repeat the layers (potatoes, onions, cheese sauce) until all ingredients are used, finishing with a layer of cheese sauce on top.

Step 12

Sprinkle the remaining 1/2 cup of cheddar cheese and 1/4 cup of Parmesan cheese over the top of the dish.

Step 13

Cover the baking dish with aluminum foil, making sure it doesn’t touch the cheese layer. Bake for 40 minutes.

Step 14

Remove the foil and bake uncovered for an additional 25-30 minutes, or until the top is golden and bubbly, and the potatoes are fork-tender.

Step 15

Remove from the oven and let the dish rest for 10 minutes before serving. Garnish with additional thyme if desired. Serve warm.

Nutrition Facts

Serving size	(2296.2g)

Amount per serving	% Daily Value*
Calories	3520.1

Total Fat 206.5g	0%
Saturated Fat 122.0g	0%
Polyunsaturated Fat 2.0g
Cholesterol 599.3mg	0%
Sodium 6104.6mg	0%
Total Carbohydrate 299.1g	0%
Dietary Fiber 21.8g	0%
Total Sugars 47.9g
Protein 127.5g	0%

Vitamin D 268.4IU	0%
Calcium 3030.6mg	0%
Iron 13.9mg	0%
Potassium 7037.1mg	0%

*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

Source of Calories

Fat: 52.1%

Protein: 14.3%

Carbs: 33.6%