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Onion Tart bites are the little black dress of appetizers, flaky puff pastry rounds piled with jammy caramelized onions, crispy bacon, and freshly grated Parmesan that make you look like you catered your own party. I made a double batch for a holiday get together and they disappeared before our famous French onion dip even hit the table.
The onions do their slow magic on the stove while the puff pastry does all the fancy work for you.
Onion Tart Quick Look
- 🕒 Prep Time: 50 minutes
- 🌡️ Cook Time: 20 minutes
- ⏳ Total Time: 1 hour 10 minutes
- 🍽️ Serving: 15 pieces
- ⚡ Calories: 218kcal
- 🌶️ Flavor Profile: Sweet jammy onions with smoky bacon on buttery pastry
- ✋ Difficulty: Easy, the same assemble and bake rhythm as our crostini
Quick Answer
Cook diced bacon until crispy, then caramelize thinly sliced sweet onion in the bacon fat over medium low heat for 45 to 50 minutes until deep brown, stirring in fresh parsley and thyme at the end. Cut thawed puff pastry into 2 and a half to 3 inch rounds, brush with egg wash, and top each center with the caramelized onions and bacon plus a sprinkle of Parmigiano Reggiano. Bake at 450 degrees for 16 to 20 minutes until golden and serve warm.
Jump to:
Why This Recipe Works
Click to see the technique science
- Caramelizing in bacon fat doubles the flavor. The onions pick up the smoky, savory drippings as they slowly brown, so every bite tastes layered before the bacon even lands on top.
- Low and slow is the only way to jammy. The 45 to 50 minutes over medium low is what converts sharp raw onion into sweet, deeply browned jam, rushing it just steams them.
- Puff pastry does the pastry chef work. Store bought sheets bake into shattering buttery layers, all you do is cut circles.
- The egg wash is the golden secret. A quick brush gives the rounds that glossy bakery shine and helps the edges brown evenly at 450 degrees.
- A hot oven puffs before it burns. 450 degrees flashes the pastry into tall crisp layers in under 20 minutes, before the onion topping can dry out.
- Parmigiano Reggiano finishes the bite. Its salty crystals melt into the onions and tie the sweet, smoky, and buttery layers together.
Why You’ll Love This Recipe
- They look like they came from a French bakery but use exactly 10 everyday ingredients.
- The caramelized onions and bacon can be made a day ahead, so party day assembly takes 10 minutes.
- They class up any appetizer spread, the fancy neighbor to our crispy onion petals.
Key Ingredients
Ten ingredients, and the onions plus bacon do all the heavy lifting.
- Puff pastry: Two thawed sheets, kept cold until cutting. The frozen aisle does the laminating so you do not have to.
- Sweet onion: One large onion, sliced thin, cooks down into the jammy caramelized filling that makes the recipe.
- Bacon: Diced and crisped first, then its fat becomes the flavor base for caramelizing the onions.
- Parmigiano Reggiano: Freshly grated over each tart before baking, the real stuff melts into salty perfection.
- Fresh thyme and parsley: Stirred into the warm onions, they add the herby freshness that keeps rich bites tasting bright.
See recipe card for exact quantities.
Variations and Substitutions
The caramelized onion base loves company.
- Swap the Parmesan for crumbled goat cheese or Gruyere for a more classic French bistro onion tart flavor.
- Add a few sliced mushrooms to the pan for the last 15 minutes of caramelizing for an earthy version.
- Skip the bacon and caramelize the onions in a tablespoon of butter for a vegetarian tray, they are still outstanding.
- Drizzle the baked tarts with hot honey or add a smear of our roasted garlic under the onions for extra depth.
How to Make Onion Tart
- Cook the diced bacon in a medium pan over medium heat until crispy, then let it drain on a paper towel, reserving the bacon fat in the pan.
- Add the sliced onions to the bacon fat, season with the salt and pepper, and cook on medium low heat until soft and deep brown, stirring often, about 45 to 50 minutes. Stir in the parsley and thyme and set aside.
- Preheat the oven to 450 degrees and line a sheet tray with parchment. Whisk the egg with the water in a small bowl.
- Place the puff pastry on a clean work surface and cut out circles with a 2 and a half to 3 inch cookie cutter. Arrange them on the prepared tray without touching and brush the tops with the egg wash.
- Top each round evenly with the caramelized onions and bacon right in the center, then sprinkle with the freshly grated Parmigiano Reggiano.
- Bake for 16 to 20 minutes until puffed and golden brown. Garnish with more parsley if you like and serve immediately.
Recipe Tips & Tricks
- Keep the puff pastry cold until the moment you cut it. Warm pastry gets sticky and bakes flat, cold pastry puffs into tall flaky layers.
- Do not rush the onions. Deep brown takes the full 45 to 50 minutes on medium low, if they are browning fast the heat is too high and they will taste burnt instead of sweet.
- Deglaze with a splash of water if the pan darkens. Scraping up those brown bits puts the flavor back into the onions instead of leaving it stuck to the pan.
- Leave a small bare border on each round. Toppings pushed to the very edge weigh the pastry down and stop the sides from puffing.
- Make the topping a day ahead. The onions and bacon keep covered in the refrigerator overnight, turning party day into a 10 minute assembly job.
- Serve them warm from the oven. The pastry is at peak crisp in the first half hour, re crisp leftovers in a 350 degree oven for 5 minutes.
Serving Ideas and Suggestions
These belong on the fancy end of a party spread, set them next to our classic shrimp cocktail and the table suddenly looks catered.
For a full appetizer hour, balance the rich pastry with something fresh and something fun, our cream cheese pinwheels and a crisp veggie tray round it out perfectly.
They also make a lovely lunch, two or three tarts beside a simple green salad, or serve them alongside our Southwest egg rolls when the party leans casual.
Store leftovers in an airtight container in the refrigerator up to 3 days and re crisp in a 350 degree oven for about 5 minutes. Skip the microwave, it turns the flaky pastry soft.
Onion Tart FAQs
This mini version uses puff pastry rounds topped with sweet onions caramelized in bacon fat, crispy bacon pieces, fresh thyme and parsley, and freshly grated Parmigiano Reggiano, all brushed with egg wash and baked at 450 degrees until golden.
A classic French onion tart is a full size pastry shell filled with a creamy onion custard, while these are individual bite size puff pastry rounds with a caramelized onion and bacon topping and no custard. Same sweet onion soul, party friendly format.
The caramelized onions and bacon can be made a day ahead and refrigerated, which is the time consuming part. Assemble and bake the tarts the day of serving for the flakiest pastry, they go from fridge to golden in about 20 minutes.
Usually the topping went on too wet or the oven was not hot enough. Let the caramelized onions cool slightly so excess moisture evaporates, leave a bare pastry border, and bake at a full 450 degrees so the pastry crisps before the topping soaks in.
Sweet onions like Vidalia caramelize into the mellowest, jammiest filling. Yellow onions work well too with a slightly deeper flavor. Skip red onions here, they turn muddy looking when cooked this long.
Five minutes in a 350 degree oven or a few minutes in the air fryer brings the pastry right back to crisp. The microwave technically warms them but sacrifices the flaky texture that makes them special.
Made these Onion Tart bites? Leave a comment and a star rating below, I would love to hear how fast the tray emptied!
Mini Onion Tarts
Ingredients
- 4 slices bacon diced ½-inch thick
- 1 sweet onion thinly sliced
- ¼ teaspoon black pepper
- ⅛ teaspoon kosher salt
- 1 teaspoon fresh chopped parsley plus more for garnish
- ½ teaspoon fresh chopped thyme
- 2 sheets puff pastry thawed
- 1 large egg
- 1 teaspoon water
- 2 tablespoons freshly grated Parmigiano Reggiano cheese
Instructions
- Cook the bacon first in a medium-sized pan over medium heat until crispy.
- Let drain on a paper towel, reserving bacon fat in the pan.
- Place the onions into the bacon fat, season with the salt and pepper, cook on medium-low heat until soft and deep brown color, stirring often. About 45-50 minutes. Stir in the herbs. Set aside.
- Preheat the oven to 450°F. Line a sheet tray with parchment paper, set aside.
- Place the puff pastry onto a clean work surface. Unwrap it and cut out circles with a 2 ½ to 3-inch cookie cutter. Place them not touching on the prepared sheet tray.
- Whisk the egg with the water in a small bowl.
- Brush the tops of the pastry rounds.
- Top evenly with the caramelized onions and bacon right in the center. Evenly sprinkle with the cheese.
- Bake for 16 – 20 minutes until golden brown. Garnish with more parsley, optional. Serve immediately.
Notes
- This recipe can easily be doubled.
- They can be frozen, see above on how to do that.
- Other herbs can be used if you’d like, see above on my suggestions.
- Add a dipping sauce, some of my favorites are pesto, honey mustard, etc.
- You can use any of your favorite bacon, our favorite is applewood smoked bacon.
Nutrition
Love This Recipe?
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If you cut it in squares, you don’t waste any of the puff pastry. I do that with another recipe that called for circles.
You can prepare the items separately ahead of time. Cut the pastry into rounds and freeze. Make the bacon and onions in advance, then the day of assemble and bake them off.
These look delicious. Do I have to make them the day of, or can I prepare them a few days before & pop into oven on day of? Or can I make them, bake them, freeze them, then warm in oven on day of event?
This looks amazing!! Pinned it!
These look amazing! I am pinning so I can make them for our next cocktail party.
Thanks so much!!
Wow girl these look fantastic! I must try your version.