Caramelized Onion and Gruyère Puff Pastry Tart That Your Family Will Love!

Name: Caramelized Onion and Gruyère Puff Pastry Tart
Prep time: 10 min
Cook time: 25 min
Total time: 35 min
Cuisine: French
Ingredients: 1 sheet puff pastry, thawed; 2 large onions, thinly sliced; 2 tablespoons olive oil; Salt and pepper to taste; 1 cup Gruyère cheese, grated; 1 tablespoon fresh thyme leaves; 1 egg, for egg wash

Posted on January 6, 2026

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This delicious Caramelized Onion and Gruyère Puff Pastry Tart comes together in about 30 minutes and involves minimal fuss, just one baking sheet! It’s a quick and easy weeknight meal that your whole family will adore! You can switch up the toppings based on what you have at home to make it a ‘clean out the fridge’ special or simply to cater to everyone’s tastes. It’s perfect for busy evenings or when you’re craving something warm and comforting without a hefty time commitment.

Ingredients You’ll Need

For this easy tart, you’ll be using some classic ingredients that really pack a flavorful punch. Here’s what you’ll need:

1 sheet puff pastry: Frozen, thawed, and ready to go, this will be your flaky base.
2 large onions, thinly sliced: Sweet onions, like Vidalia or yellow onions, work beautifully for caramelization.
2 tablespoons olive oil: Because everything is better with olive oil, right?
Salt and pepper to taste: Just a couple pinches will do!
1 cup Gruyère cheese, grated: It’s nutty and creamy oh, the flavor!
1 tablespoon fresh thyme leaves: They add a herbaceous touch that enhances the tart!
1 egg: For a lovely egg wash that gives your pastry a golden finish.

Here’s How It’s Done

Alright, let’s get into the fun part, making this awesome tart! Here’s the step-by-step so you can see just how easy it really is.

Preheat The Oven : Preheat your oven to 400°F (200°C). This is super important to get your pastry nice and crispy!
Caramelize the Onions : In a skillet (a good, heavy-bottom one works best), heat the olive oil over medium heat. Toss in the sliced onions and a couple pinches of salt. Cook those bad boys, stirring occasionally, until they’re a dreamy golden brown and totally caramelized, this should take about 15-20 minutes. You’ll know they’re ready when they smell fragrant and have that nice, translucent look.
Prep the Puff Pastry : While your onions are caramelizing, gently roll out the puff pastry on a floured surface to fit whatever tart pan you’re using. If you don’t have a tart pan, a baking sheet is just fine too. Just remember to trim off any excess pastry if needed!
Layer with Onions and Cheese : Spread the caramelized onions evenly over your pastry, don’t be shy, get all that goodness on there! Now, sprinkle that gorgeous Gruyère cheese on top, and add the fresh thyme leaves. Here’s where it gets really mouth-watering!
Egg Wash Time : In a small bowl, beat the egg until it’s frothy. Brush the edges of the pastry with the egg wash, that’s what will give you that golden, shiny crust.
Bake it Up : Pop your tart into the preheated oven and let it bake for about 20-25 minutes. You’re looking for that gorgeous golden color on the pastry, it’ll puff up beautifully!
Serve and Enjoy : Let it cool for a minute or two, slice it up, and serve warm. Honestly, I like to serve this with a simple side salad for a complete meal, or just on its own when I’m feeling snacky!

Why I Love This Recipe

This is my go-to recipe when I need something that feels comforting yet fancy enough for friends! I’m always a sucker for warm, savory tarts that bring people together around the table. Plus, you can totally use whatever you’ve got on hand, throw in some leftover veggies, or swap the cheese, it’s so versatile! The best part is that you’ll feel like a culinary genius, and trust me, your family will be asking for seconds.

If you loved this Caramelized Onion and Gruyère Puff Pastry Tart, be sure to check out my Red Pepper Pasta Bake, my One Pan Boursin Chicken Risotto, or my Classic Meatloaf!

Tips for Success

Quick & Easy

Comes together in under 30 minutes perfect for when you need something delicious without spending hours in the kitchen.

Minimal Cleanup

This recipe is all about the single sheet pan! You’ll love that there’s minimal cleanup, which is a big win for busy parents!

Customizable

I can’t stress this enough, switching out the ingredients is so easy! Use whatever cheese you have or toss in some roasted vegetables. The options are endless.

Comfort Food

This tart is loaded with tons of flavor. Seriously, the sweet onions, melted cheese, and flaky pastry create the ultimate comfort food dish that makes your heart sing!

Crowd-Pleaser

It’s a fantastic dish that your whole family will love, which means you’ll have happy faces around your dinner table!

What to Serve With This

For serving, I recommend pairing this tart with a light green salad, maybe tossed with some vinaigrette to balance the richness. It also pairs beautifully with a glass of white wine if you’re feeling fancy!

Storage

After you dig in, leftovers (if you have any, good luck with that!) will keep in the fridge in an airtight container for about 3-4 days.

Reheating Instructions

To reheat, pop it back into the oven for about 10 minutes at 350°F (175°C) to crisp it back up, or you can microwave it for about 30-60 seconds if you’re in a hurry, though I prefer the oven for that delicious flakiness!

Freezer Friendly

Yes! Feel free to freeze the tart before baking it. Just wrap it tightly, and it should hold up for up to 2 months. When you’re ready to bake, just add a few extra minutes to the baking time since you’re starting from frozen.

Food truly has this way of bringing people together. So, whether you’re whipping this up for your family after a long day or impressing friends at a cozy gathering, this Caramelized Onion and Gruyère Puff Pastry Tart is here to make your meals special. Enjoy every flaky bite, my friends! For more Recipes Follow Us in our Pinterest.