A Classic Cheese and Onion Flan

By
Elaine Lemm
Elaine Lemm
Elaine Lemm
Elaine Lemm is a renowned British food writer, classically trained chef, teacher, and author with over 25 years of experience writing about British food and cooking.
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Updated on 12/9/22
Tested by Tara Omidvar
Cheese and onion flan on a white plate

The Spruce Eats
Prep: 20 mins
Cook: 50 mins
Chill: 30 mins
Total: 100 mins
Servings: 6 servings
Nutrition Facts (per serving)
487 Calories
35g Fat
30g Carbs
12g Protein
Show Full Nutrition Label Hide Full Nutrition Label
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Nutrition Facts
Servings: 6
Amount per serving
Calories 487
% Daily Value*
Total Fat 35g 45%
Saturated Fat 18g 92%
Cholesterol 199mg 66%
Sodium 254mg 11%
Total Carbohydrate 30g 11%
Dietary Fiber 1g 5%
Total Sugars 3g
Protein 12g
Vitamin C 4mg 19%
Calcium 176mg 14%
Iron 2mg 13%
Potassium 202mg 4%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

Do not confuse a classic cheese and onion flan with a quiche. While this baked egg recipe may resemble the traditional French dish, the flan is made differently and tastes a little different. It is the traditional British version of the ubiquitous quiche and, for many Brits, is the stuff of memories. Those memories being school lunches, summer meals, afternoon tea, and dinners with cheese and onion flan served alongside a salad and often boiled new potatoes.

"Heavenly oniony cheesy flan! The crust recipe is everything! I recommend rolling the crust as thin as the recipe says, or it might turn out a bit soggy. Otherwise, you can roll it thicker and blind bake the crust first." —Tara Omidvar

Cheese and onion flan on a white plate with a slice removed
A Note From Our Recipe Tester

Ingredients

For the Pastry:

  • 200 grams all-purpose flour

  • 110 grams cubed unsalted butter, or an equal mix of butter and lard

  • 1 pinch kosher salt

  • 2 to 3 tablespoons ice water

For the Filling:

  • 55 grams unsalted butter

  • 2 tablespoons extra-virgin olive oil, or sunflower oil

  • 1 large yellow onion, finely sliced

  • 3 to 4 large eggs (200 milliliters)

  • 75 grams aged cheddar cheese, coarsely grated

  • 2 to 3 tablespoons chopped parsley

  • 1 cup milk

  • Kosher salt, to taste

  • Freshly ground black pepper, to taste

Steps to Make It

  1. Gather the ingredients.

    Ingredients to make a crust for cheese and onion flan gathered

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  2. Place the flour, butter (or butter and lard mix), and salt into a large, roomy mixing bowl. Rub the butter into the flour until it resembles sand.

    Butter, flour, and salt mixed in a bowl

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  3. Add the water a little at a time and bring the mixture together to create a soft dough.

    Flan pastry dough in a bowl

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  4. Form the pastry into a disc, wrap in plastic wrap, and chill in the refrigerator for 30 minutes.

    Dough wrapped in plastic wrap

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  5. While the pastry is resting, prepare the filling.

    Ingredients for cheese and onion flan filling gathered

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  6. Heat the butter and oil in a saucepan. Once melted, add the sliced onion and sauté over medium heat to soften (but not brown). Place the softened onion onto a dinner plate and leave to cool. 

    Onions cooking in a pot on the stove

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  7. Preheat the oven to 400 F / 204 C. Roll the pastry to 5 millimeters thickness and line a greased, 10-inch loose-bottomed tart tin. Chill in the refrigerator while you make the remaining filling. 

    Lined tart tin with pastry

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  8. Put the eggs into a large measuring jug and whisk them. Add the cooled onion, grated cheese, and parsley. Stir in the milk. Season with a little salt and black pepper. 

    Cheese and onion flan filling in a measuring cop

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  9. Take the pastry case from the refrigerator, place it on the middle shelf of the preheated oven, and carefully pour in the egg-cheese mixture until it is two-thirds full. Do not overfill as the flan will rise while cooking.

    Cheese and onion flan in the oven

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  10. Bake for 25 to 40 minutes until the top is golden brown and set, but not completely solid when gently pressed in the center.

    Cheese and onion flan cooling on a cutting board

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  11. Remove from the oven and rest for 5 minutes before serving.

    Cheese and onion flan cooling on a wire wrack

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  12. The flan is lovely warm but can also be eaten cold. 

    Cheese and onion flan cut into slices on a plate

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Tip

  • For a crisper crust on the bottom, you can blind bake the pie crust first before adding the filling. After rolling out the dough and lining the tart tin, place the tin in the refrigerator or freezer to give the dough a chance to rest and firm up; otherwise the crust could shrink and pull back while being par-baked in the oven.

Recipe Variations

  • Add crisped bacon pieces or tiny cubes into the egg for the meat-eaters. 
  • Use a different cheese; crumbly blue is amazing. 
  • Change or add a different herb. Basil and tarragon are good choices.

What's the Difference Between Flan and Quiche?

Flan, in the British sense, is an open-faced pie or tart with a savory or sweet filling. This can include egg-based pies also called quiche. Quiche is a French dish that is a savory egg tart and can include other fillings like ham, cheese, and vegetables. Flan is also a term used for a Spanish and Latin dessert of set vanilla custard with a caramel sauce.

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