Description
A comforting and indulgent Southern-style baked casserole featuring sweet onions, a creamy cheese sauce, and a crunchy breadcrumb topping.
Ingredients
Scale
- 3 large sweet onions (Vidalia or Walla Walla), peeled and thinly sliced
- 8 tablespoons unsalted butter, divided
- 1 teaspoon olive oil
- 1/2 teaspoon salt, plus more to taste
- 1/4 teaspoon freshly ground black pepper, plus more to taste
- 1/2 teaspoon garlic powder
- 1/4 teaspoon onion powder
- 1/4 teaspoon smoked paprika
- 1/4 cup all-purpose flour
- 2 cups whole milk, warmed
- 1 cup heavy cream
- 8 ounces mozzarella cheese, freshly shredded or cubed
- 4 ounces provolone cheese, freshly shredded or thinly sliced
- 1/2 cup grated Parmesan cheese, divided
- 1 cup Panko breadcrumbs
- 2 tablespoons fresh parsley, chopped (optional, for garnish)
Instructions
- Preheat your oven to 375°F (190°C) and grease a 9×13-inch baking dish with butter or non-stick spray.
- Peel and slice the onions into 1/4-inch-thick rings or half-moons.
- In a large skillet, melt 3 tablespoons of butter with 1 teaspoon of olive oil over medium heat. Add the sliced onions and toss to coat.
- Season with salt, pepper, garlic powder, onion powder, and smoked paprika. Cook for about 15–20 minutes until translucent and tender.
- Transfer softened onions to a mixing bowl and set aside. In the same skillet, melt the remaining 3 tablespoons of butter and whisk in the flour for 1–2 minutes to form a roux.
- Gradually whisk in the warmed milk and then the heavy cream, stirring until thickened.
- Lower the heat and stir in the mozzarella, provolone, and half of the Parmesan cheese until melted. Add salt and pepper to taste.
- Pour the cheese sauce over the onions and fold until combined.
- In a small bowl, mix the Panko breadcrumbs with the remaining Parmesan, drizzle with melted butter, and toss to moisten.
- Spoon the onion mixture into the baking dish, spread evenly, and top with the Panko mixture.
- Bake for 30–35 minutes, until bubbling and golden brown. Tent with foil if browning too quickly.
- Let rest for 10–15 minutes before serving. Garnish with chopped parsley.
Notes
For extra crunch, broil the topping for 1-2 minutes at the end, watching closely to prevent burning.
- Prep Time: 15 minutes
- Cook Time: 35 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: Southern
Nutrition
- Serving Size: 1 serving
- Calories: 400
- Sugar: 6g
- Sodium: 600mg
- Fat: 20g
- Saturated Fat: 10g
- Unsaturated Fat: 8g
- Trans Fat: 0g
- Carbohydrates: 45g
- Fiber: 2g
- Protein: 10g
- Cholesterol: 50mg
Keywords: onion casserole, cheesy side dish, Southern cooking, baked onions