Classic French Onion Tart

Name: Classic French Onion Tart
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Ingredients: 1 Sheet Frozen Puff Pastry; 1/2 Cup Shredded Gruyere Cheese; 1 Teaspoon Fresh Thyme Leaves; 3 Sweet Yellow Onions (sliced thin); 1 Egg; 1 Tablespoon Water

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Most delicious and easy appetizer, this Classic French Onion Tart is so perfect for spring entertaining! Made with only four ingredients and quick to make, you will love throwing this savory tart together for all of your gatherings.

A puff pastry crust with sliced onions cut into squares.

A perfect spring appetizer that you are going to love to make over and over again! This savory tart is made with only four simple ingredients and the purest and most delicious french flavors. Flakey puff pastry is the base for this tart, topped with shredded gruyere cheese, sliced sweet onions and fresh thyme leaves make this Classic French Onion Tart an easy and delicious starter or side for your next gathering.

I love using puff pastry and always keep some on hand to be able to create quick and easy appetizers that feel super fancy but take no time at all to assemble. Another favorite savory tart is our Heirloom Tomato Tart or for something sweet this French Apple Tart can be make with puff pastry as well! .

Ingredients

A sheet of puff pastry next to a cutting board with sliced onions and a pink bowl with shredded cheese.

Puff Pastry-Frozen and store bought puff pastry makes this French Onion Tart so delicious and flakey! If you are ambitious and want to make homemade puff pastry you can, but frozen is as good!
Onions-Sweet yellow onions sliced thin!
Cheese- You can change up the cheese to your liking, but my favorite is shredded Gruyere Cheese paired with the puff pastry and onions. To make this more an Italian profile you could also use parmesan cheese or a mixture of a few cheeses you love together.
Herbs- Fresh thyme leaves adds a delicious flavor, but could also be replaced with fresh rosemary.

Step-by-Step Directions

A sheet of puff pastry on a sheet pan topped with shredded cheese and thyme leaves.

Once the puff pastry is thawed out, roll out a sheet of frozen puff pastry onto a half sheet baking pan that is lined with parchment paper
Sprinkle the top of the puff pastry sheet with shredded gruyere cheese and fresh thyme leaves leaving a half in around the edge

A sheet of puff pastry on a sheet pan topped with shredded cheese and sliced onions next to a bowl of shredded cheese and thyme.

Slice the onions and place them on top of the shredded cheese, slightly overlapping
Brush the edges of the puff pastry with egg wash, fold in the edges and press down with a fork

A puff pastry crust with sliced onions on top with fresh thyme leaves

Bake the French Onion Tart in the oven for 45-50 minutes or until the puff pastry is gold brown and the onions are fully cooked through
Serve warm and Enjoy!

Tips and FAQS To Make The Best Onion Tart

Frozen Puff Pastry
I love keeping a box of frozen puff pastry in my freezer for last minute quick and easy appetizers like our favorite Prosciutto Parmesan Twists.

Cheese Variations
If you are not a lover of Gruyere cheese, replace it with parmesan cheese or spread a thin layer of Boursin Cheese and it will still taste amazing!

Can I make this onion tart a day in advance?

I recommend making this tart the day you are going to serve it because the puff pastry will be super fresh and flakey.

How do I store the left over onion tart?

If you have left overs, place the slices in a ziplock bag or airtight container and in the refrigerator for 1-2 days. When you are ready to eat it, place it in the oven for 8-10 minutes to crisp up the puff pastry.

Can I use pie dough for the crust?

Yes! You can definitely use a pie dough instead of the puff pastry but you will not get the same flakey texture.

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