Walla Walla Sweet Onion Swiss Cheese Casserole

Indulge in the comforting flavors of Walla Walla Sweet Onion Swiss Cheese Casserole, a rich and savory side dish that celebrates the natural sweetness of caramelized Walla Walla onions. Perfect for holiday gatherings or weeknight dinners, this casserole features layers of tender onions blanketed in a creamy Swiss cheese sauce and topped with a golden, buttery panko breadcrumb crust. With hints of parmesan, garlic, and fresh parsley adding depth, this recipe creates an irresistible medley of flavors and textures. Easy to prepare and bursting with cheesy goodness, this dish pairs beautifully with roasted meats, hearty vegetables, or fresh salads. Treat your taste buds to this warm, decadent bake—it’s comfort food at its finest!

Nutriscore Rating: 62/100

Prep Time:20 mins

Cook Time:45 mins

Total Time:65 mins

Servings: 6

Ingredients

• 3 large Walla Walla sweet onions
• 4 tablespoons unsalted butter
• 3 tablespoons all-purpose flour
• 2 cups whole milk
• 0.5 cups heavy cream
• 2 cups shredded Swiss cheese
• 0.5 cups parmesan cheese
• 1 cup panko breadcrumbs
• 2 tablespoons olive oil
• 1 teaspoon kosher salt
• 0.5 teaspoons black pepper
• 0.5 teaspoons garlic powder
• 2 tablespoons fresh parsley

Directions

Step 1

Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish and set aside.

Step 2

Peel and thinly slice the Walla Walla sweet onions into half-moon shapes.

Step 3

In a large skillet, melt 2 tablespoons of butter over medium heat. Add the onions and sauté until caramelized, about 10-12 minutes. Stir occasionally to prevent burning.

Step 4

While the onions cook, prepare the sauce. In a medium saucepan, melt the remaining 2 tablespoons of butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to form a roux.

Step 5

Gradually add the milk and heavy cream to the roux, whisking constantly to ensure a smooth sauce. Cook until the mixture thickens, about 3-5 minutes.

Step 6

Remove the sauce from heat and stir in 1.5 cups of Swiss cheese, 0.25 cups of parmesan cheese, salt, pepper, and garlic powder. Mix until the cheese is fully melted and incorporated.

Step 7

Spread the caramelized onions evenly in the prepared baking dish. Pour the cheese sauce over the onions, spreading it out with a spatula to cover evenly.

Step 8

In a small bowl, combine the panko breadcrumbs with the olive oil, remaining 0.5 cups of Swiss cheese, 0.25 cups of parmesan cheese, and parsley. Sprinkle this mixture evenly over the top of the casserole.

Step 9

Bake the casserole in the preheated oven for 25-30 minutes, or until the top is golden brown and bubbling.

Step 10

Remove from the oven and let cool for 5 minutes before serving.

Step 11

Garnish with additional fresh parsley if desired.

Nutrition Facts

Serving size	(1650.3g)

Amount per serving	% Daily Value*
Calories	2915.5

Total Fat 220.7g	0%
Saturated Fat 114.4g	0%
Polyunsaturated Fat 3.2g
Cholesterol 587.0mg	0%
Sodium 1988.7mg	0%
Total Carbohydrate 136.8g	0%
Dietary Fiber 10.3g	0%
Total Sugars 57.2g
Protein 111.9g	0%

Vitamin D 262.7IU	0%
Calcium 3218.1mg	0%
Iron 6.9mg	0%
Potassium 1894.7mg	0%

*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: 66.6%

Protein: 15.0%

Carbs: 18.4%