Mona's Onion Casserole

Indulge in the warm and savory comfort of Mona's Onion Casserole, a rich, cheesy dish that transforms humble sweet onions into a show-stopping centerpiece. Perfectly caramelized onions are enveloped in a creamy cheddar-Parmesan cheese sauce, then topped with golden, crispy panko breadcrumbs for an irresistible crunch. The secret lies in the luxurious combination of whole milk, heavy cream, and two types of cheese, creating a velvety texture that contrasts beautifully with the crispy topping. Infused with a hint of fresh thyme and baked to bubbly perfection, this casserole is perfect for family dinners, potlucks, or holiday tables. Easy to prepare and bursting with indulgent flavor, Mona's Onion Casserole is sure to become your new favorite comfort food.

Nutriscore Rating: 57/100

Prep Time:15 mins

Cook Time:45 mins

Total Time:60 mins

Servings: 6

Ingredients

• 4 large Sweet onions
• 4 tablespoons Unsalted butter
• 2 tablespoons All-purpose flour
• 1 cup Whole milk
• 1 cup Heavy cream
• 2 cups Sharp cheddar cheese, shredded
• 1 cup Parmesan cheese, grated
• 1 teaspoon Salt
• 0.5 teaspoon Black pepper
• 1 cup Panko breadcrumbs
• 1 tablespoon Olive oil
• 1 teaspoon Fresh thyme leaves (optional)

Directions

Step 1

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

Step 2

Peel and slice the sweet onions into thin rings. This will allow them to cook evenly.

Step 3

In a large skillet over medium heat, melt 3 tablespoons of butter. Add the sliced onions and cook, stirring occasionally, for 15-20 minutes, or until they become golden brown and caramelized. Remove from heat and set aside.

Step 4

In a medium saucepan, melt the remaining 1 tablespoon of butter over medium heat. Whisk in the flour and cook for 1-2 minutes to form a roux.

Step 5

Gradually whisk in the milk and heavy cream. Stir constantly, allowing the mixture to thicken, about 3-4 minutes.

Step 6

Once the sauce has thickened, reduce the heat to low and stir in the shredded cheddar cheese and half of the Parmesan cheese. Add the salt, black pepper, and thyme leaves (if using). Stir until the cheese is melted and the sauce is smooth.

Step 7

Fold the caramelized onions into the cheese sauce, ensuring they are evenly coated. Transfer the mixture to the prepared casserole dish, spreading it out evenly.

Step 8

In a small bowl, mix the panko breadcrumbs with olive oil and the remaining Parmesan cheese. Sprinkle the breadcrumb mixture evenly over the top of the casserole.

Step 9

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

Step 10

Remove the casserole from the oven and let it rest for 5 minutes before serving. Enjoy this comforting and flavorful dish!

Nutrition Facts

Serving size	(1730.7g)

Amount per serving	% Daily Value*
Calories	3257.3

Total Fat 248.6g	0%
Saturated Fat 146.9g	0%
Polyunsaturated Fat 1.6g
Cholesterol 713.3mg	0%
Sodium 5712.3mg	0%
Total Carbohydrate 145.6g	0%
Dietary Fiber 16.1g	0%
Total Sugars 55.3g
Protein 114.0g	0%

Vitamin D 155.4IU	0%
Calcium 3001.7mg	0%
Iron 6.6mg	0%
Potassium 1817.2mg	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: 68.3%

Protein: 13.9%

Carbs: 17.8%