Onion Casserole
Indulge in the rich, savory goodness of this Onion Casserole, a comforting dish that transforms humble yellow onions into a show-stopping centerpiece. Featuring sweet caramelized onions layered with a velvety Gruyere-infused béchamel sauce, this recipe is topped with a crispy panko-Parmesan crust that adds the perfect crunch to every bite. Enhanced with aromatic garlic and fresh thyme, this casserole strikes a delectable balance between creamy and crispy textures. Ideal as a crowd-pleasing side dish or a vegetarian main course, this dish is easy to prepare with just 20 minutes of hands-on time. Perfect for holidays, potlucks, or cozy weeknight dinners, this Onion Casserole is sure to become a new family favorite.
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Recipe Information
Ingredients
- 6 medium Yellow onions
- 4 tablespoons Butter
- 2 tablespoons All-purpose flour
- 1.5 cups Whole milk
- 0.5 cups Heavy cream
- 1.5 cups Shredded Gruyere cheese
- 1 teaspoon Salt
- 0.5 teaspoons Ground black pepper
- 0.5 teaspoons Garlic powder
- 1 cup Panko breadcrumbs
- 0.5 cups Parmesan cheese, grated
- 2 tablespoons Olive oil
- 1 teaspoon Fresh thyme leaves
Instructions
Preheat your oven to 375°F (190°C). Grease a 9x9-inch casserole dish with butter or non-stick spray and set aside.
Peel and slice the yellow onions into thin, even rings. Separate the rings to ensure even cooking.
In a large skillet over medium heat, melt 3 tablespoons of butter. Add the sliced onions and sauté for 15-20 minutes, stirring occasionally, until the onions are soft and caramelized. Reduce heat if necessary to avoid burning.
While the onions are caramelizing, prepare the béchamel sauce. In a medium saucepan, melt the remaining 1 tablespoon of butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to create a roux.
Gradually whisk in the milk and heavy cream. Continue cooking, whisking frequently, until the mixture thickens into a smooth sauce, about 3-4 minutes. Remove from heat and stir in 1 cup of shredded Gruyere cheese, salt, pepper, and garlic powder until smooth. Set aside.
Once the onions are caramelized, transfer them to the greased casserole dish. Pour the cheese sauce evenly over the onions, gently stirring to combine and coat the onions.
In a small mixing bowl, combine the panko breadcrumbs, grated Parmesan cheese, olive oil, and fresh thyme leaves. Stir until the breadcrumbs are evenly coated with the oil.
Sprinkle the breadcrumb mixture evenly over the onion and cheese mixture in the casserole dish.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and crispy.
Remove the casserole from the oven and allow it to cool for 5 minutes before serving. Enjoy as a side dish or main course!
Nutrition Facts
Calories |
2635 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 194.3 g | 249% | |
| Saturated Fat | 99.0 g | 495% | |
| Polyunsaturated Fat | 4.5 g | ||
| Cholesterol | 516 mg | 172% | |
| Sodium | 5078 mg | 221% | |
| Total Carbohydrate | 132.7 g | 48% | |
| Dietary Fiber | 14.1 g | 50% | |
| Total Sugars | 50.4 g | ||
| Protein | 92.7 g | 185% | |
| Vitamin D | 5.2 mcg | 26% | |
| Calcium | 2690 mg | 207% | |
| Iron | 5.9 mg | 33% | |
| Potassium | 1693 mg | 36% | |
*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.
