Potato Gratin with Parmesan and Caramelized Onions

Elevate your side dish game with this rich and comforting Potato Gratin with Parmesan and Caramelized Onions. Thinly sliced russet potatoes are layered with sweet, golden caramelized onions, a luscious blend of heavy cream and milk infused with garlic and fresh thyme, and a perfectly balanced duo of Parmesan and Gruyere cheeses. Baked to golden, bubbly perfection, this indulgent gratin is the ultimate crowd-pleaser, perfect for holidays, dinner parties, or a cozy family meal. The creamy texture and savory flavors marry beautifully, making every bite irresistible. Plus, it’s surprisingly simple to prepare, with just 20 minutes of prep time! Serve it alongside roasted meats or enjoy it as a standalone star—either way, it’s guaranteed to steal the show. Keywords: potato gratin, caramelized onions, Parmesan, Gruyere, creamy potato casserole, holiday side dish.

Nutriscore Rating: 61/100

Prep Time:20 mins

Cook Time:90 mins

Total Time:110 mins

Servings: 6

Ingredients

• 4 large Russet potatoes
• 2 medium Yellow onions
• 3 tablespoons Unsalted butter
• 2 cloves Garlic cloves, minced
• 2 cups Heavy cream
• 1 cup Whole milk
• 1 cup Parmesan cheese, grated
• 1 cup Gruyere cheese, shredded
• 1 tablespoon Olive oil
• 1.5 teaspoons Salt
• 1 teaspoon Black pepper
• 1 teaspoon Fresh thyme leaves

Directions

Step 1

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

Step 2

Peel and slice the russet potatoes into 1/8-inch-thick rounds. Use a mandoline slicer for even slices if available.

Step 3

Peel and thinly slice the onions. Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a skillet over medium heat. Add the onions and cook, stirring occasionally, until they become soft and golden brown, about 20 minutes. Set aside.

Step 4

In a small saucepan, melt the remaining 2 tablespoons of butter over medium heat. Add the minced garlic and sauté for 1 minute until fragrant. Stir in the heavy cream, whole milk, salt, pepper, and fresh thyme. Heat the mixture until warm, but do not let it boil. Remove from heat.

Step 5

Layer one-third of the potato slices evenly in the bottom of the baking dish, slightly overlapping them. Sprinkle one-third of the caramelized onions over the potatoes, followed by one-third of the grated Parmesan and shredded Gruyere cheeses. Repeat this process two more times, finishing with a final layer of cheese on top.

Step 6

Pour the warm cream mixture evenly over the layered potatoes and cheese, ensuring all layers are moistened.

Step 7

Cover the baking dish with aluminum foil and bake for 50 minutes. Remove the foil and bake for an additional 20-25 minutes, or until the top is golden brown and the potatoes are tender when pierced with a fork.

Step 8

Let the gratin cool for 10 minutes before serving. Garnish with additional fresh thyme if desired.

Nutrition Facts

Serving size	(2409.8g)

Amount per serving	% Daily Value*
Calories	4209.4

Total Fat 278.1g	0%
Saturated Fat 159.8g	0%
Polyunsaturated Fat 1.6g
Cholesterol 802.3mg	0%
Sodium 6134.1mg	0%
Total Carbohydrate 299.7g	0%
Dietary Fiber 25.4g	0%
Total Sugars 35.0g
Protein 110.0g	0%

Vitamin D 131.4IU	0%
Calcium 2517.8mg	0%
Iron 15.6mg	0%
Potassium 7553.3mg	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: 60.4%

Protein: 10.6%

Carbs: 28.9%