Onion Tart

Indulge in the rich, savory elegance of a classic French-inspired Onion Tart—perfect for elevating any meal or gathering. This recipe layers buttery, flaky homemade pastry with deeply caramelized yellow onions gently enhanced by a touch of sugar and fresh thyme. The creamy, custard-like filling of eggs, heavy cream, and nutty grated Gruyère cheese bakes to golden perfection, infusing every bite with luxurious flavor. Ideal as an appetizer, brunch centerpiece, or light dinner, this tart pairs wonderfully with a crisp green salad or a chilled glass of white wine. With just 30 minutes of prep time and a handful of pantry staples, this Onion Tart is a show-stopping yet accessible dish you'll return to time and time again. Keywords: onion tart, caramelized onions, Gruyère cheese tart, French tart recipe, savory tart recipe.

Nutriscore Rating: 52/100

Prep Time:30 mins

Cook Time:50 mins

Total Time:80 mins

Servings: 6

Ingredients

• 120 grams unsalted butter
• 180 grams all-purpose flour
• 1 teaspoon salt
• 2 tablespoons cold water
• 3 large yellow onions
• 2 tablespoons olive oil
• 1 teaspoon sugar
• 1 teaspoon fresh thyme leaves
• 120 milliliters heavy cream
• 2 large eggs
• 100 grams gruyère cheese
• 1 teaspoon black pepper

Directions

Step 1

Preheat the oven to 180°C (350°F).

Step 2

In a large mixing bowl, combine the flour and 1/2 teaspoon of salt. Add the diced butter and rub it into the flour using your fingertips until the mixture resembles breadcrumbs.

Step 3

Add cold water one tablespoon at a time and mix until the dough comes together. Form it into a ball, wrap in plastic wrap, and refrigerate for 20 minutes.

Step 4

Slice the onions thinly. Heat olive oil in a large skillet over medium heat. Add the onions and a pinch of salt, reducing heat to low after 5 minutes. Cook, stirring occasionally, for 20–25 minutes, or until caramelized.

Step 5

Stir in the sugar and thyme, then cook for another 2 minutes. Remove from heat and let cool.

Step 6

Roll out the chilled dough on a floured surface to fit a 9-inch tart pan. Line the pan with the dough, trimming excess, then prick the base all over with a fork.

Step 7

Blind bake the tart shell: Line it with parchment paper and fill it with pie weights or dried beans. Bake for 15 minutes. Remove the weights and parchment, then bake for another 5 minutes until lightly golden.

Step 8

Whisk together the eggs, heavy cream, grated gruyère cheese, black pepper, and remaining salt in a mixing bowl.

Step 9

Spread the caramelized onions evenly over the tart shell. Pour the egg and cream mixture over the onions, ensuring it is evenly distributed.

Step 10

Bake the onion tart in the preheated oven for 25–30 minutes, or until the filling is set and golden brown.

Step 11

Allow the tart to cool slightly before slicing. Serve warm or at room temperature.

Nutrition Facts

Serving size	1140.6 grams (1140.6g)

Amount per serving	% Daily Value*
Calories	2942

Total Fat 214.90g	276%
Saturated Fat 110.80g	554%
Polyunsaturated Fat 4.40g
Cholesterol 868mg	289%
Sodium 3295mg	143%
Total Carbohydrate 186.70g	68%
Dietary Fiber 13.30g	48%
Total Sugars 24.50g
Protein 66.90g	134%

Vitamin D 106IU	530%
Calcium 1224mg	94%
Iron 12mg	67%
Potassium 1128mg	24%

*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: 65.6%

Protein: 9.1%

Carbs: 25.3%