Caramelized Onion & Brussels Sprouts Tarts

These little squares of heaven have a buttery, flaky puff pastry dough crust topped with quick caramelized onion, sliced Brussels sprouts, crumbled blue cheese and a fruity burst of pomegranate seeds.

They’re a tasty appetizer for entertaining or even just a quiet Friday night in. You can make them ahead of time and serve them warm or cold, making them a versatile appetizer for all occasions!

Overhead shot of Brussels sprouts tarts on a parchment lined baking sheet

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How do I make these gorgeous caramelized onion and Brussels sprouts tarts?

Yay! I’m so glad you asked. They’re EASY. Just take a look through the photos below!

There’s no rolling pin required, no measuring, no fussy kitchen gadgets. You’ll use the seams of the puff pastry dough as your cutting guide which makes life so much easier. Then a quick score around the edges creates the perfect crust.

You’ll top your puff pastry squares with caramelized onion, Brussels sprouts and blue cheese, then give the edges a quick egg wash and it’s into the oven they go!

Once they’re baked up all buttery and flaky, you’ll garnish with a bit more crumbled blue cheese and then a sprinkle of pomegranate seeds.

That’s it! Easy peasy.

Collage of two photos showing puff pastry being cut into rectangles and then into squares
Overhead shot of puff pastry squares being scored with a knife to create the crust

How do I know when my onions are caramelized?

There are varying degrees of caramelized onions. You can caramelize onions for just 10 minutes or you can caramelize them for an hour or more!

You’ll see in my Caramelized Onion & Fig Jam Tart recipe that we caramelized the onions for 60 minutes. That left them very deep, dark brown and almost paste-like in texture.

In this recipe, we are doing a quick caramelized onion, so we’ll only let the onions go for 20 minutes or so. This will yield a lighter brown onion that is still caramelized and sweet, but holds the shape of a sliced onion.

You are more than welcome to take these caramelized onions all the way if you’d like to cook them for the full hour. You can wait to deglaze them with wine until the end, or you can do it a couple times throughout the process.

The photos below should help you to know when your onions are done.

You’ll see in the third photo there are lots of brown bits stuck to the bottom of the pan, and in the fourth photo they are gone. This is because the moisture from the wine allows the brown bits to release so you are able to scrape them from the bottom and stir in all that delicious flavor.

I actually cooked these onions for just a couple more minutes after the fourth photo was taken and you can see how much darker brown they got just in those couple minutes.

Don’t forget to deglaze with the wine! And pour yourself a glass while you’re at it!

Can I make these puff pastry tarts ahead of time?

Yes! If you’re into making things ahead of time, you could easily assemble the tarts, freeze them on a parchment lined baking sheet and then transfer them to an airtight container and freeze for up to a month.

The day before baking, allow the tarts to thaw in the fridge overnight on a parchment lined baking sheet and then bake.

You could also assemble these tarts and then refrigerate them for up to 24 hours before baking. Puff pastry is pretty forgiving, but it needs to be kept cold in order to rise properly when baked. So don’t let these tarts sit out on your counter or get anywhere near room temp before you bake them.

Collage of two photos showing puff pastry squares being topped with caramelized onion and then sliced Brussels sprouts
Overhead shot of puff pastry squares being garnished with crumbled blue chese

Do I have to use puff pastry?

Not necessarily. You could use pie crust or even crescent rolls if yo’ure in a pinch.

However, puff pastry has the perfect buttery flakiness needed for this dish, so it’s best to stick to the recipe here and use traditional puff pastry sheets.

Where can I find puff pastry?

Luckily you can find puff pastry in the freezer section of most grocery stores near the dessert items. Pepperidge Farm is my favorite reasonably priced brand that can be found in most super markets.

Overhead shot of puff pastry squares being brushed with an egg wash before baking

Can I use another veggie instead of Brussels sprouts?

Sure! Just make sure you slice them thinly so they’ll cook up in the same amount of time. Broccoli, cabbage or bok choy would be delicious in place of the Brussels sprouts in this recipe!

Overhead shot of puff pastry Brussels sprouts tart after coming out of the oven

Can I use another cheese instead of blue cheese for these tarts?

Yes! Any crumbly, tangy cheese will do! Gorgonzola is another great option, but luckily blue cheese is super easy to find at most super markets.

Pan of puff pastry Brussels sprouts tarts topped with pomegranate seeds on a parchment lined baking sheet

What should I serve with these puff pastry tarts?

These tarts are the perfect appetizer addition to any party, or you could serve them as a light dinner along with a green salad or a plate of pasta.

Dinner doesn’t always have to be meat and potatoes. Great creative, the possibilities are endless!

Overhead shot of puff pastry tarts on a white serving platter

Did you make this recipe? Leave a review!

If you make these Greek Potato Wedges I’d love to hear how they turn out! Feel free to leave a rating and comment below. I love hearing from you guys and respond to each and every comment that I receive!

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Caramelized Onion & Brussels Sprouts Tarts

  • Author: Midwest Foodie
  • Prep Time: 10 minutes
  • Cook Time: 40 minutes
  • Total Time: 50 minutes
  • Yield: 18 tarts
  • Category: Appetizer
  • Method: Oven
  • Cuisine: American


These little squares of heaven have a buttery, flaky puff pastry dough crust with quick caramelized onion, sliced Brussels sprouts, crumbled blue cheese and a fruity burst from pomegranate seeds.    


  • 1 (17.3 oz.) package (2 sheets) puff pastry, thawed
  • 2.5 tablespoons butter
  • splash dry white wine
  • 1 yellow onion, halved and sliced in 1/8″ thick slices
  • about 1 cup 1/8-1/4″ thick sliced Brussels sprouts
  • 5 oz. crumbled blue cheese
  • 1 beaten egg + splash of water
  • 1/2 cup pomegranate seeds
  • Kosher salt


  1. Heat butter in a large pot over medium heat. Add onion along with a pinch of salt. Cook for 20 minutes, stirring every few, until the onions are brown and caramelized. Deglaze the pan with a splash of white wine and scrape all the yummy bits off the bottom. Set aside. 
  2. Preheat oven to 400 degrees.
  3. Unfold puff pastry and cut along the seams, creating 6 rectangles. Cut each rectangle into 3 squares. 
  4. Place squares on a parchment lined baking sheet. Score the squares with a knife about a 1/2″ from the edge, creating the crust. 
  5. Divide caramelized onion evenly between the tarts. 
  6. Divide Brussels sprouts evenly between the tarts. 
  7. Divide blue cheese evenly between the tarts, reserving 1-2 tablespoons for garnish. 
  8. Brush the crust of each tart with the egg wash. 
  9. Bake for 18-20 minutes or until the edges and bottom of the dark are golden brown. 
  10. Garnish with pomegranate seeds and the remaining blue cheese. 
  11. Serve warm or at room temperature and enjoy!


The easiest way to thaw puff pastry is in the fridge overnight. If you don’t have time to do that, you can leave it out on the counter for about 40 minutes or so. 

Keywords: easy, simple, quick, appetizer, recipe, party, holiday, family, vegetarian, puff pastry, pomegranate

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Caramelized Onion & Brussels Sprouts Tarts | Midwest Foodie

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