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.

Nutriscore Rating: 61/100

Prep Time:20 mins

Cook Time:45 mins

Total Time:65 mins

Servings: 6

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)

Directions

Step 1

Preheat your oven to 375°F (190°C) and lightly grease a 9x9-inch baking dish.

Step 2

Peel and thinly slice the yellow and red onions. Finely chop the green onions, separating the white and green parts.

Step 3

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.

Step 4

Add the thyme, salt, and black pepper to the skillet, stirring to combine.

Step 5

Sprinkle the flour over the caramelized onions and stir until fully incorporated. Cook for 1-2 minutes to remove the raw flour taste.

Step 6

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.

Step 7

Remove the skillet from heat and stir in the Gruyère cheese until melted and fully combined.

Step 8

Transfer the onion mixture to the prepared baking dish and spread it out evenly.

Step 9

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.

Step 10

Bake the casserole in the preheated oven for 20-25 minutes, or until the top is golden brown and crispy.

Step 11

Remove the casserole from the oven and let it rest for 5-10 minutes before serving.

Step 12

Garnish with the chopped green parts of the green onions and fresh parsley, if desired.

Nutrition Facts

Serving size	1543.9 grams (1543.9g)

Amount per serving	% Daily Value*
Calories	2081

Total Fat 146.00g	187%
Saturated Fat 79.40g	397%
Polyunsaturated Fat 1.30g
Cholesterol 388mg	129%
Sodium 5688mg	247%
Total Carbohydrate 118.70g	43%
Dietary Fiber 16.20g	58%
Total Sugars 40.60g
Protein 74.40g	149%

Vitamin D 7IU	34%
Calcium 2018mg	155%
Iron 5mg	27%
Potassium 1423mg	30%

*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: 63.0%

Protein: 14.3%

Carbs: 22.8%