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This onion tart recipe is the perfect appetizer. Once you take your first bite of these sweet onion tartlets, you’re going to forget that there is anything else on your plate. They’d also be a fun way to add mini onion tarts to your latest charcuterie board creation!

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onion tarts on a blue plate with greens around them

What are onion tarts?

Onion tarts should really be their own food group. They’re the perfect little puff pastries filled with simple ingredients that are a great appetizer at parties and holidays. 

Why You’ll Love This Recipe

  • What I love about making these french onion tartlets is that they’re fast and simple, but they don’t look like it.
  • Use phyllo shells for the crust – no mess!
  • Caramelized onions are the star of the dish.

Ingredients Needed

  • Olive oil – Or extra virgin olive oil.
  • Sweet onions – dice them small. You can use Vidalia or white onions.
  • Garlic – Mince your own or use a paste.
  • Salt – To taste. 
  • Ground black pepper – To taste. 
  • Fresh thyme leaves – Fresh is always best but you can also use dried thyme if needed.
  • Worcestershire sauce – Adds a deep flavor to the onions making them taste like they’ve cooked all day.
  • Beef stock – You can substitute vegetable stock for a vegetarian option.
  • Shredded Gruyere cheese – This is my favorite type of cheese, but you could use shredded provolone too. 
  • Phyllo shells – Buying them premade from the store saves a ton of time. 
onion tarts on a blue plate with greens around them

How to caramelize onions

To get the most flavor out of this French onion tart, you need to be sure to caramelize the onions! A caramelized onion tart can’t be made without the star ingredient, right? 

  • The biggest tip to caramelizing onions is that you need to follow the directions in the recipe card below, and don’t forget to scrape the pan as you’re adding the ingredients. 
  • I always use a wooden spoon when I’m stirring and scraping the pan with the onions in it because I don’t want to scratch the pan. 

How to make Mini Onion Tarts

  • Preheat. Preheat the oven to 350 degrees. Add parchment paper to a cookie sheet to make cleanup a breeze. 
  • Cook the onions. Add the oil to a skillet over medium heat. Add the onions and cook, then lower the heat to medium-low and let them cook for about 10 minutes, stirring often. 
  • Add the salt, pepper, garlic, and thyme and cook for another 5 minutes. Stir often. Pour in the Worcestershire sauce and stock and stir. Grab your wooden spoon and scrape all the bits off the bottom of the pan. Cook the onions until the liquid is gone and the onions are soft, which will take another 3-5 minutes. Take the pan off the heat. 
  • Fill the phyllo shells. Put the shells on the baking sheet and fill them with the onion mixture. Add the cheese on top. 
  • Bake. Place the baking sheet in the oven and bake for 6-9 minutes. Serve warm, and enjoy! 
onion tarts on a blue plate with greens around them

Storing and Freezing 

These simple tarts are best served warm and fresh. If you have leftovers, you can store them in the fridge, but I would recommend eating them the day that they’re made.

To reheat them, just pop them in the oven or the air fryer for a short amount of time, and they’ll crisp back up a bit! 

I don’t recommend freezing them because the texture won’t thaw out the same. Just make them and eat them that day! 


How do you reheat onion tarts?

While I prefer reheating in the air fryer or the oven, you can also pop them in the microwave for a short period of time.  The air fryer will just take a couple of minutes, as will the oven. These two methods will help to make the phyllo cups a little bit crispier in texture than the microwave option. 

How long do onions take to caramelize?

I would give yourself a prep time of about 15-20 minutes to caramelize onions all the way. It can take longer or less, depending on how many onions you have in the skillet. 

What can I substitute for the phyllo cups?

If you don’t want to use Phyllo cups, you can use puff pastry instead. These might be a bit thicker in texture, but they’ll still be divine. 

Have You Made This Recipe?

Leave a rating by clicking the stars below!

onion tarts on a blue plate with greens around them

Onion Tarts Recipe

5 from 8 votes
These amazing savory tarts will be great for any occasion!
Prep Time 10 minutes
Cook Time 30 minutes
Total Time 40 minutes
Yield 30 servings
Serving Size 1 serving


  • 1 tablespoon olive oil
  • 2 medium sweet onions diced
  • 2 cloves garlic minced
  • ½ teaspoon salt
  • ¼ teaspoon ground black pepper
  • 2 springs of fresh thyme leaves
  • 2 teaspoons Worcestershire sauce
  • ¼ cup beef stock
  • ½ cup 40g finely shredded Gruyere cheese
  • 30 phyllo shells from 2 1.9 ounce/54 g packages of 15
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  • Preheat oven to 350°F. Line a cookie sheet with parchment paper or foil for easy cleanup.
  • Heat olive oil in a 10-inch skillet over medium heat. Add the diced onion and cook, lowering the heat to medium-low, for about 10 minutes, stirring often.
  • Add the garlic, salt, pepper, and thyme and cook an additional 5 minutes over medium-low heat, stirring often.
  • Add the Worcestershire sauce and beef stock and stir to combine. Use a wooden spoon or spatula to scrape up the brown bits on the bottom of the pan. Cook until liquid is cooked off and onions are golden and soft, another 3-5 minutes. Remove from heat.
  • Place phyllo shells on prepared cookie sheet. Fill each with approximately 1 teaspoon of onion mixture. Top with shredded cheese.
  • Bake 6-9 minutes, or until cheese is melted and tart shells are heated through. Serve warm.
  • Store leftovers in refrigerator; these are best the same day they’re made but can be reheated in the oven or air fryer.

Recipe Notes

  • Tip: Can’t find the phyllo shells? Use slices of baguette to make a crostini instead.

Recipe Nutrition

Serving: 1serving | Calories: 33kcal | Carbohydrates: 4g | Protein: 1g | Fat: 2g | Saturated Fat: 0.5g | Polyunsaturated Fat: 0.1g | Monounsaturated Fat: 1g | Cholesterol: 2mg | Sodium: 73mg | Potassium: 36mg | Fiber: 0.2g | Sugar: 1g | Vitamin A: 25IU | Vitamin C: 1mg | Calcium: 28mg | Iron: 0.1mg
Nutritional information not guaranteed to be accurate
Course Appetizer
Cuisine American

Other Favorite Appetizers

Mini Onion Tarts are bites of french onion tart in phyllo dough – this is the perfect easy appetizer recipe for a party!


Dorothy Kern

Welcome to Crazy for Crust, where I share recipes that are sometimes crazy, often with a crust, and always served with a slice of life.

5 from 8 votes (7 ratings without comment)

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  1. I’m not able to eat anything with Worcestershire Sauce. Is there an alternative ingredient I could use instead? I’d love to try this, it sounds delicious!