Walla Walla Onion Casserole

Indulge in the comforting, savory flavors of a Walla Walla Onion Casserole, a creamy and cheesy baked dish that celebrates the natural sweetness of Walla Walla onions. This delightful recipe features tender caramelized onion rings layered beneath a rich, velvety cheddar and Parmesan cheese sauce, all crowned with a crispy, golden panko breadcrumb topping. Perfect as a side dish or a warm, filling centerpiece, this casserole is easy to assemble with a straightforward roux-based sauce and just the right blend of wholesome ingredients. Ready in under an hour, it’s ideal for family dinners, potlucks, or holiday gatherings. Garnish with fresh parsley for a pop of color, and enjoy a dish that's as comforting as it is delectable!

Nutriscore Rating: 57/100

Prep Time:15 mins

Cook Time:45 mins

Total Time:60 mins

Servings: 6

Ingredients

• 4 large Walla Walla onions
• 4 tablespoons unsalted butter
• 3 tablespoons all-purpose flour
• 2 cups whole milk
• 1 cup heavy cream
• 1.5 cups shredded cheddar cheese
• 0.5 cups grated Parmesan cheese
• 1 teaspoon salt
• 0.5 teaspoons black pepper
• 1 cup panko breadcrumbs
• 1 tablespoon olive oil
• 2 tablespoons fresh parsley (optional, for garnish)

Directions

Step 1

Preheat your oven to 375°F (190°C). Grease a 9x13-inch casserole dish lightly with butter or cooking spray and set aside.

Step 2

Peel and thinly slice the Walla Walla onions into rings. Set aside.

Step 3

In a large skillet, melt 2 tablespoons of butter over medium heat. Add the sliced onions and cook for 10-12 minutes, stirring occasionally, until the onions are soft and just starting to caramelize. Remove from heat.

Step 4

In a medium saucepan, melt the remaining 2 tablespoons of butter over medium heat. Once melted, whisk in the flour to form a roux and cook for 1-2 minutes until lightly golden.

Step 5

Gradually pour in the milk and heavy cream, whisking constantly to ensure no lumps form. Cook for 3-4 minutes until the mixture thickens.

Step 6

Stir in the shredded cheddar cheese and Parmesan cheese until melted and smooth. Season with salt and black pepper, then remove from heat.

Step 7

Layer the cooked onions in the prepared casserole dish. Pour the cheese sauce evenly over the onions, ensuring all are well coated.

Step 8

In a small bowl, combine the panko breadcrumbs with the olive oil, mixing gently until the breadcrumbs are evenly coated. Sprinkle the breadcrumb mixture evenly over the top of the casserole.

Step 9

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

Step 10

Remove the casserole from the oven and let it rest for 5 minutes before serving. Garnish with chopped fresh parsley, if desired.

Nutrition Facts

Serving size	(1888.4g)

Amount per serving	% Daily Value*
Calories	2995.0

Total Fat 226.9g	0%
Saturated Fat 131.7g	0%
Polyunsaturated Fat 1.9g
Cholesterol 644.2mg	0%
Sodium 4775.2mg	0%
Total Carbohydrate 146.7g	0%
Dietary Fiber 12.3g	0%
Total Sugars 67.1g
Protein 91.5g	0%

Vitamin D 214.7IU	0%
Calcium 2475.4mg	0%
Iron 5.3mg	0%
Potassium 1955.8mg	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: 68.2%

Protein: 12.2%

Carbs: 19.6%