Three Onion Casserole
Indulge in the rich, savory flavors of this Three Onion Casserole, a comforting side dish that celebrates the distinct profiles of yellow, red, and green onions. Slow-cooked caramelized onions form the heart of this dish, enhanced by a luscious, thyme-scented cream sauce and melted Gruyère cheese. Topped with a golden, crunchy layer of panko breadcrumbs and Parmesan, this baked casserole offers a perfect contrast in texture. Ready in just over an hour, it’s an elegant addition to holiday spreads or weeknight dinners. Serve it warm for a burst of hearty, sweet, and savory flavors that will have everyone coming back for seconds.
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Recipe Information
Ingredients
- 3 large Yellow onions
- 2 medium Red onions
- 5 stalks Green onions (scallions)
- 3 tablespoons Unsalted butter
- 1 tablespoon Olive oil
- 1 teaspoon Fresh thyme
- 2 tablespoons All-purpose flour
- 1.5 cups Chicken or vegetable broth
- 0.5 cup Heavy cream
- 1 cup Gruyère cheese (shredded)
- 0.75 cup Panko breadcrumbs
- 0.25 cup Parmesan cheese (grated)
- 1 teaspoon Salt
- 0.5 teaspoon Black pepper
- 2 tablespoons Fresh parsley (optional, for garnish)
Instructions
Preheat your oven to 375°F (190°C) and lightly grease a 9x9-inch baking dish.
Peel and thinly slice the yellow and red onions. Finely chop the green onions, separating the white and green parts.
In a large skillet, heat the butter and olive oil over medium heat. Add the yellow and red onions, along with the white parts of the green onions. Cook for 15-20 minutes, stirring occasionally, until the onions are softened and caramelized.
Add the thyme, salt, and black pepper to the skillet, stirring to combine.
Sprinkle the flour over the caramelized onions and stir until fully incorporated. Cook for 1-2 minutes to remove the raw flour taste.
Gradually add the chicken or vegetable broth to the skillet, about 1/4 cup at a time, stirring constantly to create a smooth sauce. Reduce the heat to low and stir in the heavy cream. Simmer for 3-4 minutes, until the mixture thickens slightly.
Remove the skillet from heat and stir in the Gruyère cheese until melted and fully combined.
Transfer the onion mixture to the prepared baking dish and spread it out evenly.
In a small bowl, combine the panko breadcrumbs, Parmesan cheese, and a drizzle of olive oil. Sprinkle this mixture evenly over the onions in the baking dish.
Bake the casserole in the preheated oven for 20-25 minutes, or until the top is golden brown and crispy.
Remove the casserole from the oven and let it rest for 5-10 minutes before serving.
Garnish with the chopped green parts of the green onions and fresh parsley, if desired.
Nutrition Facts
Calories |
374 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 24.0 g | 31% | |
| Saturated Fat | 13.3 g | 66% | |
| Polyunsaturated Fat | 0.0 g | ||
| Cholesterol | 64 mg | 21% | |
| Sodium | 947 mg | 41% | |
| Total Carbohydrate | 25.3 g | 9% | |
| Dietary Fiber | 2.9 g | 10% | |
| Total Sugars | 6.3 g | ||
| Protein | 13.3 g | 27% | |
| Vitamin D | 0.2 mcg | 1% | |
| Calcium | 350 mg | 27% | |
| Iron | 1.3 mg | 7% | |
| Potassium | 268 mg | 6% | |
*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.
