Caramelized Onion Mustard Tart
Transform your next gathering with the irresistible flavors of this Caramelized Onion Mustard Tart, a sophisticated yet easy-to-make appetizer that's sure to impress. Featuring sweet, golden caramelized onions atop a flaky puff pastry base, this tart is elevated by a tangy layer of Dijon mustard, a sprinkle of fresh thyme, and a generous amount of melted Gruyère cheese. With the perfect balance of savory sweetness and herbaceous notes, it's an elegant option for brunches, dinner parties, or a cozy night in. Ready in just over an hour and baked to golden perfection, this tart is best served warm or at room temperature for a crowd-pleasing dish that’s as visually stunning as it is delicious. Keywords: caramelized onion tart, puff pastry tart, Gruyère cheese tart, Dijon mustard appetizer, savory tart recipe.
Log this recipe in SnapCalorie
Recipe Information
Ingredients
- 2 tablespoons unsalted butter
- 1 tablespoon olive oil
- 4 large yellow onions
- 1 teaspoon salt
- 1 teaspoon granulated sugar
- 1 sheet store-bought puff pastry sheet
- 3 tablespoons Dijon mustard
- 1 tablespoon fresh thyme leaves
- 1 cup grated Gruyère cheese
- 1 large egg
- 1 tablespoon water
Instructions
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a large skillet, melt the butter with the olive oil over medium heat.
Slice the onions thinly, then add them to the skillet. Sprinkle them with the salt and sugar.
Cook the onions for 25-30 minutes, stirring occasionally, until they are soft, deeply golden, and caramelized. Remove the skillet from the heat and let the onions cool slightly.
Unroll the puff pastry sheet and place it on the prepared baking sheet. Prick the center with a fork, leaving a 1-inch border on all sides.
Spread the Dijon mustard evenly over the pricked area of the pastry.
Scatter the caramelized onions over the mustard layer, spreading them evenly.
Sprinkle fresh thyme leaves and grated Gruyère cheese over the onions.
In a small bowl, beat the egg with the water to create an egg wash. Brush the edges of the pastry with the egg wash for a golden finish.
Bake the tart in the preheated oven for 20-25 minutes, or until the pastry is puffed and golden brown.
Remove the tart from the oven and allow it to cool slightly before slicing and serving. Serve warm or at room temperature.
Nutrition Facts
Calories |
2634 | ||
|---|---|---|---|
% Daily Value* |
|||
| Total Fat | 180.1 g | 231% | |
| Saturated Fat | 81.2 g | 406% | |
| Polyunsaturated Fat | 3.3 g | ||
| Cholesterol | 402 mg | 134% | |
| Sodium | 5332 mg | 232% | |
| Total Carbohydrate | 201.1 g | 73% | |
| Dietary Fiber | 15.8 g | 56% | |
| Total Sugars | 33.3 g | ||
| Protein | 62.6 g | 125% | |
| Vitamin D | 1.9 mcg | 10% | |
| Calcium | 1190 mg | 92% | |
| Iron | 8.9 mg | 49% | |
| Potassium | 1240 mg | 26% | |
*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.
