Potato Onion Gratin
Indulge in the ultimate comfort food with this Potato Onion Gratin, a rich and creamy side dish that’s perfect for any occasion. Layers of velvety Yukon Gold potatoes and sweet yellow onions are bathed in a decadent blend of heavy cream, whole milk, and aromatic spices like garlic, thyme, and a hint of nutmeg. Topped with melted Gruyère and Parmesan cheeses, this gratin bakes to golden perfection, delivering a bubbling, cheesy crust that’s impossible to resist. With only 20 minutes of prep time and a heavenly aroma that fills your kitchen, this dish is ideal for holidays, dinner parties, or cozy family meals. Serve it alongside roasted meats or a crisp salad for a sophisticated yet soul-warming meal. Keywords: potato onion gratin, cheesy potato gratin, creamy potato casserole, holiday side dish.
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Recipe Information
Ingredients
- 6 medium (about 2.5 lbs) Yukon Gold potatoes
- 2 large Yellow onions
- 2 cups Heavy cream
- 1 cup Whole milk
- 2 cups Gruyère cheese (shredded)
- 1 cup Parmesan cheese (grated)
- 2 tablespoons Unsalted butter
- 2 cloves Garlic
- 2 teaspoons (chopped) Fresh thyme
- 1 teaspoon Salt
- 0.5 teaspoon Ground black pepper
- 0.25 teaspoon Nutmeg (optional)
Instructions
Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish with 1 tablespoon of the unsalted butter.
Peel the potatoes and slice them thinly (about 1/8-inch thick) using a sharp knife or a mandoline slicer. Place the slices in a bowl of cold water to prevent browning while you prepare the other ingredients.
Peel and slice the onions thinly. Mince the garlic.
In a medium saucepan, heat the heavy cream and milk over medium-low heat. Add the minced garlic, thyme, salt, black pepper, and nutmeg (if using). Heat until warm but not boiling, then remove from heat.
Layer half of the potato slices evenly on the bottom of the prepared baking dish. Arrange half of the sliced onions on top of the potatoes.
Pour half of the warmed cream mixture over the potatoes and onions. Sprinkle 1 cup of the shredded Gruyère cheese evenly over the layer.
Repeat the layering process with the remaining potatoes, onions, and cream mixture. Top with the remaining Gruyère cheese and the Parmesan cheese.
Dot the top of the gratin with the remaining 1 tablespoon of unsalted butter, cut into small pieces.
Cover the baking dish tightly with aluminum foil and bake in the preheated oven for 40 minutes.
Remove the foil and continue baking for an additional 30-35 minutes, or until the potatoes are tender and the top is golden and bubbling.
Let the gratin cool for 10 minutes before serving. Garnish with additional thyme, if desired.
Nutrition Facts
Calories |
9070 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 336.1 g | 431% | |
| Saturated Fat | 200.1 g | 1000% | |
| Polyunsaturated Fat | 0.3 g | ||
| Cholesterol | 1017 mg | 339% | |
| Sodium | 8306 mg | 361% | |
| Total Carbohydrate | 1248.2 g | 454% | |
| Dietary Fiber | 97.8 g | 349% | |
| Total Sugars | 71.6 g | ||
| Protein | 307.2 g | 614% | |
| Vitamin D | 3.0 mcg | 15% | |
| Calcium | 6193 mg | 476% | |
| Iron | 52.0 mg | 289% | |
| Potassium | 29777 mg | 634% | |
*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.
