
Brie and Apple Crostini with Onion Jam (The Perfect Sweet & Savory Appetizer)
There are some appetizers that feel a little extra special—the kind that look impressive on a platter but are secretly very simple to make. These Brie and Apple Crostini with Onion Jam fall squarely into that category. They’re sweet, savory, creamy, crunchy, and just a little bit fancy… without being fussy. My Mom introduced these to me when I visited for Christmas. She had tried them at a party and got the recipe so she could make them for us during the holidays. She was excited about them for good reason…we all LOVED them!! We all devoured them! I could not wait to get home and share the recipe here!
I know this is going to be a favorite appetizer to make for gatherings, holiday parties, or even a cozy date night at home. The combination of rich, melty brie, crisp apple slices, and deeply caramelized onion jam piled onto toasted ciabatta is pure magic. Every bite has contrast: crunchy and creamy, sweet and tangy, rich and fresh.
Why You’ll Love This Recipe
- Perfect for entertaining – Looks beautiful on a platter and can be prepped in stages.
- Amazing flavor balance – Sweet onions, tangy vinegar, creamy brie, and crisp apples.
- Versatile – The onion jam is delicious on so many other things (more on that below!).
- Simple ingredients – Nothing fancy or hard to find.
And the real star of the show? That homemade onion jam. It sounds gourmet, but it’s surprisingly easy and makes your kitchen smell absolutely incredible while it simmers.

Let’s Talk About the Onion Jam
This onion jam is slow-simmered until thick, glossy, and spoonable, with a deep sweet-and-savory flavor thanks to the vinegar, sugar, thyme, and bay leaf. A little fruit pectin helps it thicken perfectly and gives it that “jammy” texture that clings beautifully to the crostini. Now that I have a jar of this I have found lots of uses for it!
Bonus: Make it ahead! It keeps well in the fridge for a week or two and is incredible:
- In grilled cheese sandwiches
- On toast with goat cheese
- As a pizza topping
- On burgers or sandwiches
You might find yourself making it just for those uses.

A Little Hosting Tip
If you’re serving these for a party, you can:
- Make the onion jam a day or two ahead
- Slice the bread and toast it shortly before serving
- Assemble just before guests arrive so everything stays crisp and fresh
These crostini are one of those recipes that always get compliments—and people are always surprised when you tell them how simple they are. Sweet, savory, creamy, crunchy… they truly check all the boxes.
If you make them, don’t be surprised if the onion jam becomes a new fridge staple.
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Brie and Apple Crostini with Onion Jam
Ingredients
For the Onion Jam:
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1 1/2 teaspoons fruit pectin
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1 1/2 teaspoons warm water
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1 Tablespoon unsalted butter
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6 cups thinly sliced yellow onions (about 3 large onions)
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1/2 cup white wine vinegar
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1 cup white sugar
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2 teaspoons chopped fresh thyme
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1 bay leaf
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2 teaspoons kosher salt
For the Crostini:
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1 Honeycrisp or Granny Smith apple
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4 ounces ripe Brie cheese
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1 ciabatta bread or baguette, sliced
Instructions
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In a small bowl, mix the fruit pectin with the warm water and set aside to bloom.
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Melt the butter in a large saucepan over medium heat. Add the sliced onions and cook until they are golden brown, soft, and translucent, about 15–20 minutes.
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Add the vinegar, sugar, thyme, bay leaf, and salt. Reduce the heat to low and stir in the bloomed pectin.
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Simmer for another 15–20 minutes, stirring occasionally, until the mixture thickens and coats the back of a spoon.
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Transfer the onion jam to a small mason jar and let cool.
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Toast the bread slices on both sides until golden brown. You can do this on a BBQ, in a toaster oven, or under the broiler in the oven.
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Thinly slice the Brie and the apple.
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To assemble: lay slices of Brie on the toasted bread, top with apple slices, and spoon some onion jam over the top.
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Serve immediately and watch them disappear.
Recipe Source: From my Mom but adapted from the Founding Farmer’s Cookbook (Nevin Martell)

Oh that is such a good idea! I made a turkey brie and apple panini with it one day and it was so yummy!!!
They really are so good!!!
Thanks Leah!
This looks sooo good! Thanks for sharing! 💜
I LOVE this appetizer! Oh my!!
Oh my goodness this recipe is to die for!!! Love it so much. Also used the leftover onion jam for ham sandwich and it was delicious!!!