Sweet Onion Puff Pastry Tart

sliced sweet onion tart with fresh thyme

My sweet onion puff pastry tart is an easy peasy but oh-so-elegant tart for lunch, brunch, or cut it into small squares for an appetizer. Use Vidalia, Maui, Texas, or generic sweet onions for this fabulous tart.

sweet onion puff pastry tart, sliced

my sweet onion puff pastry tart riffs on the famous Southern Vidalia onion pie

With Vidalia onion season starting up this week, it seems fitting to feature sweet onions in my tart. The concept comes from the Southern classic pie, made with lots of sweet onions in a mayo and cheese base. Instead of a pastry crust we’re using easy puff pastry, and instead of a deep dish pie, we’re going with a thin, slab style situation. When you slice them extra thin, the tangle of sweet strings looks so pretty!

slicing up a sweet onion puff pastry

my sweet onion puff pastry tart is a 4 ingredient wonder

Aside from onion salt, pepper, and olive oil, there are really only 4 ingredients to this easy tart…

  • vidalia onion ~ one onion, sliced super thin, is enough to fill this tart shell. What if you can’t find Vidalia onions? Use any sweet variety, they’ll be labeled right next to the white, yellow, and red onions in your supermarket.
  • a sheet of frozen puff pastry ~ thawed overnight in the fridge. I’m always up for an easy elegant appetizer or light dinner, and that box of puff pastry in the freezer is my best friend.
  • mayonnaise ~ don’t worry, if you absolutely don’t do mayo, there are alternatives listed down below.
  • shredded cheese ~ you can use white cheddar, or an Italian blend. A pre-shredded bag is just fine for this recipe, and there are so many choices out there. You can shred your own cheese if you prefer. Use a relatively sharp cheese so the flavor comes through.

sweet Vidalia onions and thyme

no need to pre-cook the sweet onions, use them raw

The beauty of this recipe is that you can use the sweet onions raw. They’re mild and the thin slices cook up perfectly in the short time the tart is in the oven. In fact, Vidalia onions are reputed to be so mild you can eat them just like an apple ~ not that I recommend that 😉 This tart is the perfect venue for these amazing onions.

vidalia onion tart

how to get puff pastry to crisp up even in the center ~ no more raw dough!

In our testing for this recipe we experienced the problem of the bottom of the pastry crust not getting done in the center. The edges bake up lovely, but the crust under the filling, especially towards the center of the tart, tended to be flat and not cooked through, so we set out to fix that issue. Here’s what we found:

  • Roll out your dough as usual, and run the tip of a sharp knife around the edge, about a 1/2 inch in, to make a guideline for the crust.
  • Take a fork and prick the crust all over, inside the frame. This will help the bottom from puffing up too much.
  • Bake the crust at 400F for 10 minutes.
  • Remove from the oven and spread your filling onto the hot crust, again, inside the frame. If it has puffed up, no worries, the spreading will flatten it back down. Add the toppings.
  • Put the tart immediately back in the oven and finish baking per the recipe. The crust will be evenly crisp, even under your filling.

slicing up a sweet onion puff pastry tart

variations on a theme

  • you can cut your sheet of puff pastry into four pieces if you want to bake individual tarts. Proceed in the same way as for the larger tart, and cooking time will be shorter by about 10 minutes or so.
  • instead of the mayo/cheese mixture you can spread a layer of Boursin cheese, creme fraiche, soft goat cheese, or mascarpone cheese on the pastry as a base for your onions.

more ways to use a package of puff pastry

sliced sweet onion tart with fresh thyme
5 from 3 votes

Sweet Onion Puff Pastry Tart

Sweet Onion Puff Pastry Tart is an easy peasy but oh-so-elegant tart for lunch or brunch. Cut it into small squares for an appetizer. Use Vidalia, Maui or generic sweet onions for this fabulous tart.
Course Appetizer
Cuisine American
Prep Time 10 minutes
Cook Time 35 minutes
Total Time 45 minutes
Yield 6 servings
Calories 447kcal
Author Sue Moran


  • 1/2 cup mayonnaise
  • 1/4 tsp onion salt
  • fresh cracked black pepper, to taste
  • 3/4 cup shredded sharp white cheddar cheese
  • 1 sheet frozen puff pastry
  • 1 medium sweet onion, peeled and sliced into very thin rings I use my mandoline slicer set at 1/8 inch
  • 1 Tbsp olive oil, for brushing
  • a few sprigs fresh thyme for serving


  • Preheat oven to 400F and line a large baking sheet with parchment paper.
  • Mix together the mayo, onion salt, pepper, and cheese. Set aside.
  • Gently roll out the puff pastry so that it is a little longer and wider, about 2 iches longer and an inch wider. (Puff pastry is already rolled, but you want it just a little bit thinner.) With the tip of a sharp knife, score all the way around the outside of the pastry, about 1/2 inch in from the edge, to make a frame. With a fork, pierce the pastry inside your frame several times.
  • Bake the puff pastry in the preheated oven for 10 minutes. It might get quite puffy in the middle, no worries.
  • Remove the pastry from the oven, deflate the center a little bit by piercing it with a fork, and gently spread the mayo mixture across the whole rectangle inside the scored lines. Top with the thinly sliced onion (you may not need to use all your slices, depending on the size of your onion), and brush lightly with the olive oil.
  • Immediately return to the oven and bake for 25-30 more minutes until the pastry is a rich golden brown. Scatter some fresh thyme leaves over the tart and serve warm.


Calories: 447kcal | Carbohydrates: 23g | Protein: 7g | Fat: 37g | Saturated Fat: 9g | Trans Fat: 1g | Cholesterol: 23mg | Sodium: 409mg | Potassium: 108mg | Fiber: 1g | Sugar: 3g | Vitamin A: 155IU | Vitamin C: 3mg | Calcium: 119mg | Iron: 1mg
The nutritional information for recipes on this site is provided as a courtesy and although theviewfromgreatisland.com tries to provide accurate nutritional information, these figures are only estimates.

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    Leave a Reply

    Please rate this recipe!

  • Reply
    May 18, 2022 at 9:11 am

    5 stars
    I love this recipe. So easy, impressive & delicious. What more could we want?

    In your list of sweet onions never forget Walla Wallas. The Northwest turns on them.

    • Reply
      Sue Moran
      May 18, 2022 at 9:16 am

      I’ll add them, I never seem to see them in my stores!

  • Reply
    April 27, 2021 at 1:28 pm

    Beautiful tart. I have a totally separate questions: The picture of the muffin on the home page looks so good but I cannot find it in the muffin category. I was hoping you can tell me what it is. Thank you. I also searched quick breads thinking maybe a recipe was made into muffins but I did not see anything that resembled the muffin picture.

    • Reply
      Sue Moran
      April 27, 2021 at 2:04 pm

      You have a great eye, Candice, that’s a rhubarb muffin that’s coming up soon on the blog, sorry to tease! I’ll get it out asap.

      • Reply
        April 28, 2021 at 9:03 am

        I cannot wait. Love rhubarb and have had rhubarb cobbler for my birthday many times. Thank you. I will be looking for it.

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