Potatoes and Caramelized Onion Casserole

Indulge in the ultimate comfort food with this rich and satisfying Potatoes and Caramelized Onion Casserole. Perfectly soft layers of thinly sliced russet potatoes are paired with sweet, golden caramelized onions and a creamy garlic-infused sauce, then topped with a delectable blend of Gruyere and Parmesan cheeses. Slow-baked to perfection, this casserole achieves a melt-in-your-mouth texture with irresistible cheesy, golden-brown edges. Infused with fresh thyme and finished with a sprinkle of parsley, this dish is both elegant and hearty—ideal for holiday gatherings or weeknight dinners alike. Simple yet elevated, this recipe is a crowd-pleaser that combines the best of rustic flavors with a gourmet twist.

Nutriscore Rating: 63/100

Prep Time:20 mins

Cook Time:90 mins

Total Time:110 mins

Servings: 6

Ingredients

• 6 medium russet potatoes
• 3 large yellow onions
• 4 tablespoons butter
• 2 tablespoons olive oil
• 3 large garlic cloves
• 1.5 cups heavy cream
• 0.5 cups milk
• 1 cup grated Gruyere cheese
• 0.5 cups shredded Parmesan cheese
• 1 teaspoon fresh thyme leaves
• 1.5 teaspoons salt
• 1 teaspoon black pepper
• 2 tablespoons fresh parsley (optional, for garnish)

Directions

Step 1

Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch casserole dish with butter or olive oil.

Step 2

Peel the potatoes and cut them into thin, uniform slices (about 1/8-inch thick). Set the slices aside in a large bowl of cold water to prevent browning while you prepare the onions.

Step 3

Peel and thinly slice the onions. Heat a large skillet over medium heat and add the butter and olive oil.

Step 4

Once the butter has melted, add the sliced onions to the skillet. Cook, stirring occasionally, for 25-30 minutes until the onions are golden brown and caramelized. If the pan gets too dry, add a splash of water to prevent burning.

Step 5

While the onions are caramelizing, mince the garlic and prepare the cream mixture. In a medium saucepan, combine the heavy cream, milk, minced garlic, thyme, salt, and black pepper. Warm over low heat for 5 minutes, stirring occasionally, then remove from heat.

Step 6

Drain the potato slices and pat them dry with a clean kitchen towel or paper towels.

Step 7

Assemble the casserole by layering half of the potato slices in the prepared dish, slightly overlapping them. Sprinkle half of the caramelized onions and half of the Gruyere cheese over the potatoes.

Step 8

Repeat with the remaining potato slices, caramelized onions, and Gruyere cheese.

Step 9

Pour the warmed cream mixture evenly over the layered potatoes and onions. Gently press down on the layers with the back of a spoon to ensure the liquid distributes evenly.

Step 10

Cover the dish tightly with aluminum foil and bake for 60 minutes in the preheated oven.

Step 11

Remove the foil, sprinkle the Parmesan cheese evenly over the top, and bake uncovered for an additional 20-25 minutes until the potatoes are tender and the top is golden and bubbly.

Step 12

Let the casserole cool for 5-10 minutes before serving. Garnish with fresh parsley, if desired.

Nutrition Facts

Serving size	(2237.0g)

Amount per serving	% Daily Value*
Calories	3775.6

Total Fat 245.3g	0%
Saturated Fat 132.8g	0%
Polyunsaturated Fat 4.1g
Cholesterol 642.3mg	0%
Sodium 5645.2mg	0%
Total Carbohydrate 284.5g	0%
Dietary Fiber 27.0g	0%
Total Sugars 37.9g
Protein 90.3g	0%

Vitamin D 69.4IU	0%
Calcium 2031.6mg	0%
Iron 14.3mg	0%
Potassium 6874.7mg	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: 59.6%

Protein: 9.7%

Carbs: 30.7%