Golden sweet onion tart with Gruyère and herbs is a rich, savory dish featuring caramelized onions nestled in a flaky tart crust, topped with melted cheese and fresh herbs. I love how this recipe turns humble onions into the star of the show—sweet, golden, and deeply flavorful. It’s elegant enough for a brunch or gathering, but simple enough to enjoy as a weeknight treat.
Why You’ll Love This Recipe
I love this recipe for its balance of flavors and textures—the natural sweetness of caramelized onions, the creamy sharpness of Gruyère, and the buttery crispness of the tart crust. The herbs brighten everything up and make the whole dish feel refined without being fussy. Whether I’m serving it warm or at room temperature, it always feels like something special.
Ingredients
(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)
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Sweet onions (such as Vidalia or Walla Walla)
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Olive oil or butter (for caramelizing)
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Gruyère cheese (shredded)
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Eggs
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Heavy cream or half-and-half
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Fresh thyme or rosemary (chopped)
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Salt and pepper
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Prepared tart crust or pie dough (store-bought or homemade)
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Dijon mustard (optional, for brushing the crust base)
Directions
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I preheat the oven to 375°F (190°C) and fit the tart dough into a tart pan, trimming the edges. I prick the base with a fork and blind bake it for 10–12 minutes to prevent sogginess.
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While the crust bakes, I slice the onions thinly and cook them slowly in olive oil or butter over medium heat for 20–25 minutes until golden and caramelized. I season with salt, pepper, and herbs toward the end.
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In a bowl, I whisk together the eggs and cream with a pinch of salt and pepper.
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Once the crust has pre-baked, I optionally brush a thin layer of Dijon mustard over the base for a hint of sharpness.
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I spread the caramelized onions evenly into the crust, sprinkle the Gruyère over the top, then pour the egg mixture gently over everything.
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I bake the tart for 25–30 minutes, or until the filling is set and the top is golden and slightly puffed.
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I let the tart cool for a few minutes before slicing. It can be served warm or at room temperature.
Servings and timing
This tart serves 6 to 8, depending on slice size. It takes about 15 minutes to prep, 25 minutes to caramelize the onions, and 30 minutes to bake—so the total time is about 1 hour and 10 minutes.
Variations
Sometimes I add a sprinkle of Parmesan on top for extra depth or mix in a handful of sautéed mushrooms with the onions. I’ve used leeks instead of onions for a more delicate flavor. If I want a crustless version, I bake the filling in a greased pie dish like a frittata. And for a dairy-free twist, I use a plant-based cream and vegan cheese—it still turns out great.
Storage/Reheating
I store leftover tart slices in the fridge for up to 3 days. To reheat, I place them in a 350°F (175°C) oven for about 10–12 minutes until warmed through. Microwaving works too, but the crust stays crispier when reheated in the oven or toaster oven.
FAQs
What type of onions work best?
I use sweet onions like Vidalia, but yellow onions work too—they just take a little longer to caramelize and may need a pinch of sugar to balance the flavor.
Can I make the tart ahead of time?
Yes, I often make it a day ahead and serve it at room temperature or reheat it gently in the oven before serving.
Do I need to blind bake the crust?
Yes, blind baking helps keep the crust from getting soggy once the filling is added. It gives a firmer, crisper base.
Can I use a puff pastry instead of tart dough?
Absolutely. I’ve made this tart using puff pastry and it turns out beautifully flaky—just keep an eye on the baking time since puff pastry cooks faster.
What herbs go best with this tart?
Fresh thyme is my go-to, but rosemary or chives work well too. I sometimes sprinkle a few fresh leaves on top after baking for extra aroma.
Conclusion
Golden sweet onion tart with Gruyère and herbs is a comforting, flavorful dish that always feels just a little bit fancy. I love the way the onions melt into the creamy filling, and the crust gives it the perfect structure. Whether I’m making it for a brunch, a light dinner, or a picnic, it’s one of those recipes that always impresses with minimal effort.
