Onion Pie Casserole

Indulge in the rich, savory goodness of Onion Pie Casserole, a comforting dish that turns humble yellow onions into a show-stopping star. This recipe features caramelized onions sautéed in butter and olive oil, then mixed with thyme, Gruyère, and Parmesan cheeses to create a creamy, flavor-packed filling. Encased in a buttery, golden pie crust, this casserole is baked to perfection, offering a flaky exterior with a luscious, cheesy center. Ideal for a cozy family dinner or a brunch centerpiece, this dish combines the elegance of French cuisine with the heartiness of a home-baked pie. With simple prep and a melt-in-your-mouth flavor, Onion Pie Casserole is your go-to recipe for satisfying, rustic comfort food. Perfectly balanced and packed with flavor, it’s a must-try for onion lovers and pie enthusiasts alike!

Nutriscore Rating: 63/100

Prep Time:20 mins

Cook Time:60 mins

Total Time:80 mins

Servings: 6

Ingredients

• 4 large Yellow onions
• 3 tablespoons Unsalted butter
• 1 tablespoon Olive oil
• 1 teaspoon Salt
• 0.5 teaspoon Black pepper
• 1 teaspoon Thyme leaves
• 3 tablespoons All-purpose flour
• 1.5 cups Whole milk
• 1 cup Gruyère cheese, shredded
• 0.5 cup Parmesan cheese, grated
• 2 sheets Pre-made pie crusts
• 1 large Egg yolk
• 1 tablespoon Water

Directions

Step 1

Preheat your oven to 375°F (190°C).

Step 2

Peel and thinly slice the yellow onions into half-moons.

Step 3

In a large skillet, heat the butter and olive oil over medium heat until melted.

Step 4

Add the sliced onions, salt, and pepper. Sauté for 25-30 minutes, stirring occasionally, until the onions are caramelized and golden brown.

Step 5

Stir in the thyme leaves and cook for another 1-2 minutes. Set aside to cool slightly.

Step 6

Sprinkle the flour over the onions and mix well to coat. Gradually add the milk, stirring constantly to form a creamy mixture. Cook for 2-3 minutes until slightly thickened.

Step 7

Remove the skillet from the heat and stir in the Gruyère and Parmesan cheeses until melted and smooth.

Step 8

On a lightly floured surface, roll out one pre-made pie crust and fit it into a greased 9-inch round casserole or deep pie dish.

Step 9

Spoon the onion mixture into the pie crust, spreading it evenly.

Step 10

Roll out the second pie crust and lay it over the filling. Trim any excess crust and crimp the edges to seal.

Step 11

Whisk the egg yolk with water and brush the mixture over the top crust for a golden finish.

Step 12

Cut a few small slits in the top crust to allow steam to escape.

Step 13

Bake in the preheated oven for 35-40 minutes, or until the crust is golden brown and flaky.

Step 14

Allow the casserole to cool for 10 minutes before slicing and serving.

Nutrition Facts

Serving size	1235.9 grams (1235.9g)

Amount per serving	% Daily Value*
Calories	1636

Total Fat 115.00g	147%
Saturated Fat 59.90g	300%
Polyunsaturated Fat 1.70g
Cholesterol 481mg	160%
Sodium 4017mg	175%
Total Carbohydrate 92.70g	34%
Dietary Fiber 11.30g	40%
Total Sugars 43.90g
Protein 72.00g	144%

Vitamin D 203IU	1016%
Calcium 2138mg	164%
Iron 4mg	19%
Potassium 1576mg	34%

*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: 61.1%

Protein: 17.0%

Carbs: 21.9%