Onions Au Gratin
Indulge in the rich, comforting elegance of Onions Au Gratin, a delightful recipe that transforms humble yellow onions into a gourmet masterpiece. This dish features tender, simmered onion halves smothered in a creamy, nutmeg-infused cheese sauce made with Gruyère and Parmesan, then topped with a golden, crispy breadcrumb crust. Perfectly baked to bubbling perfection, it delivers a balance of hearty flavors and textures that make it an irresistible side dish or vegetarian centerpiece. Easy to prepare in under an hour, this dish is ideal for holidays, dinner parties, or whenever you're craving something indulgent and savory. Garnished with fresh parsley for a pop of color and freshness, Onions Au Gratin is sure to impress with its elegant simplicity and bold flavors.
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Recipe Information
Ingredients
- 4 medium Yellow onions
- 3 tablespoons Unsalted butter
- 2 tablespoons All-purpose flour
- 1.5 cups Whole milk
- 0.5 teaspoons Salt
- 0.25 teaspoons Ground black pepper
- 0.125 teaspoons Ground nutmeg
- 1 cup Gruyère cheese, shredded
- 0.5 cups Parmesan cheese, grated
- 0.5 cups Breadcrumbs
- 1 tablespoon Olive oil
- 2 tablespoons Fresh parsley, chopped (optional)
Instructions
Preheat your oven to 375°F (190°C).
Peel the onions and slice them in half crosswise. Remove a small slice from the bottom of each half so they sit flat.
Place the onion halves cut side down in a large pot and cover with water. Bring to a boil and simmer for 8-10 minutes, until just tender but not falling apart.
Drain the onions and carefully transfer them to a greased baking dish, cut side up.
In a medium saucepan, melt the butter over medium heat. Stir in the flour and cook for 1-2 minutes, stirring constantly, to form a roux.
Gradually whisk in the milk, ensuring there are no lumps. Cook, whisking constantly, until the sauce thickens, about 3-5 minutes.
Stir in the salt, pepper, and nutmeg. Remove the saucepan from heat and mix in half of the Gruyère cheese and half of the Parmesan cheese until melted and smooth.
Pour the cheese sauce evenly over the onions in the baking dish.
In a small bowl, mix the breadcrumbs with the olive oil and the remaining Gruyère cheese and Parmesan cheese.
Sprinkle the breadcrumb mixture evenly over the dish to form a topping.
Bake in the preheated oven for 20-25 minutes, or until the topping is golden brown and crisp.
Let the dish cool for 5 minutes, garnish with fresh parsley (if using), and serve warm.
Nutrition Facts
Calories |
1697 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 113.2 g | 145% | |
| Saturated Fat | 58.8 g | 294% | |
| Polyunsaturated Fat | 1.7 g | ||
| Cholesterol | 297 mg | 99% | |
| Sodium | 3668 mg | 159% | |
| Total Carbohydrate | 112.4 g | 41% | |
| Dietary Fiber | 10.2 g | 36% | |
| Total Sugars | 40.2 g | ||
| Protein | 74.3 g | 149% | |
| Vitamin D | 4.6 mcg | 23% | |
| Calcium | 2107 mg | 162% | |
| Iron | 4.8 mg | 27% | |
| Potassium | 1331 mg | 28% | |
*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.
