This puff pastry onion tart is an easy appetizer that's layered with creamy Boursin cheese, sweet red onions and finished with tangy balsamic. With just a handful of ingredients, it's simple to make and looks beautiful as part of an appetizer spread.
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About This Recipe
If you love a good shortcut in the kitchen, this easy onion tart is for you! Store-bought puff pastry is spread with creamy, herby Boursin cheese and layered with thinly sliced red onions that soften and slightly caramelize in the oven. And a final sprinkle of fresh thyme and freshly grated Parmesan cheese add even more savory flavor.
Once baked, the onion tart is finished with a drizzle of sweet and tangy aged balsamic. The acidity pairs beautifully with the slightly sweet onions and creamy herb cheese.
It’s an easy savory tart that’s perfect for casual get-togethers, holiday appetizers, or anytime you want something that looks impressive without a lot of effort. And if you love Boursin cheese, definitely add these Boursin stuffed mushrooms to the menu!
📋 Ingredients
- Puff Pastry: Puff pastry is a buttery and flaky dough that can be found in the frozen section of most grocery stores. I like keeping a box in the freezer for easy appetizers like this tart. Thaw the pastry overnight in the refrigerator or according to the package instructions.
- Red Onions: Red onions have a slightly sweeter, milder flavor and add beautiful color to the tart. Slice them thinly (a mandoline works well) so they soften and caramelize as they bake.
- Boursin Cheese: This creamy, herbed cheese is packed with garlic and herbs. Let it come to room temperature, so it’s easier to spread over the pastry.
- And if you love Boursin cheese, you must try my Boursin and steak crostini, too!
- Fresh Thyme: Thyme pairs beautifully with the sweet onions and savory cheese. Remove the leaves from the stems and scatter them over the onions.
- Parmesan Cheese: A little freshly grated Parmesan adds another savory layer. You don't need much since the Boursin is already well seasoned.
- Aged Balsamic Vinegar or Balsamic Glaze: A drizzle over the baked tart adds a sweet and tangy finish that pairs so well with the onions.
- Olive Oil and Egg: A light drizzle of olive oil helps the onions cook, while an egg wash gives the exposed pastry edges a beautiful golden finish.
See recipe card for full information on ingredients and quantities.
🍋 Substitutions and Variations
- Different Cheese: If you don't have Boursin, substitute with mascarpone or a softened cream cheese, then mix in fresh thyme, chopped chives, roasted garlic and black pepper for a similar herby flavor.
- Try Different Onions: Thinly sliced shallots or sweet yellow onions also work very well.
- Make Individual Tarts: Cut the puff pastry into 4 to 5-inch rounds, then spread each with cheese and top with sliced onions. Bake until puffed and golden, adjusting the baking time as needed.
- Other Garnish Options: Finish the tart with balsamic glaze, which is sweeter than aged balsamic vinegar. For another variation, drizzle a little honey or hot honey for a sweet and spicy finish.
⏲️ Instructions
Slice the Onions. Use a mandolin or sharp knife to evenly slice the onions thin, about ⅛ of an inch.
Spread the cheese. Spread the softened Boursin evenly inside the scored border, leaving the edges uncovered.
Layer the Tart. Arrange the sliced onions over the cheese. Brush lightly with olive oil and sprinkle with fresh thyme and grated Parmesan. Brush the exposed pastry border with beaten egg.
Bake and Serve. Bake for 20–25 minutes, or until golden brown and the onions are tender. Finish with a drizzle of aged balsamic and fresh thyme.
📍 Recipe Tips
- Keep the Puff Pastry Cold: Keep the thawed pastry cold until ready to bake for the flakiest, golden crust.
- Soften the Boursin: Let the cheese sit at room temperature for about 30 to 60 minutes so it's easy to spread.
- Slice the Onions Thinly: Use a mandoline for even, thin slices that are about ⅛ inch thick. Thicker slices may not soften as much during baking.
- Storage and Reheating: Once baked and cooled, store the tart in an airtight, paper towel-lined container in the refrigerator for up to 3 days. Reheat on a baking sheet at 325°F until warmed through and crisp.
Serving Suggestions
This savory onion tart is perfect for a holiday appetizer spread or weekend brunch. Cut it into squares for easy serving.
Serve it alongside a few of these favorites:
For brunch, pair the onion tart with a simple green salad dressed with lemon vinaigrette or serve a slice topped with a fried egg.
More Tart Recipes to Try
Onion Tart with Puff Pastry and Boursin
LittleFerraroKitchen.com
Equipment
Ingredients
- 1 sheet puff pastry thawed
- 4 ounces Boursin cheese softened to room temperature
- 1-2 small to medium red onions thinly sliced (about ⅛ inch thick)
- 2 tablespoons olive oil or as needed
- 1 teaspoon fresh thyme leaves plus more for garnish
- 1 egg beaten (for egg wash)
- Freshly cracked black pepper to taste
- Finely grated Parmesan cheese
- Balsamic for finishing
Instructions
- Prepare the puff pastry. Preheat the oven to 400°F. Unfold the puff pastry on a floured surface and lightly roll it out with a rolling pin. Then transfer to a parchment lined baking sheet.
- Score the edges. Using a sharp knife, lightly score a border about ½ inch from the edges, being careful not to cut all the way through the pastry.
- Spread the cheese. Spread the softened Boursin evenly inside the scored border, leaving the edges uncovered.
- Add the onions. Arrange the thinly sliced red onions over the cheese, slightly overlapping them.
- Season the tart. Brush the onions lightly with olive oil and sprinkle with fresh thyme and grated Parmesan.
- Brush the edges. Brush the exposed pastry border with beaten egg.
- Bake. Bake for approximately 20–25 minutes, or until the pastry is puffed and golden brown and the onions are tender.
- Garnish and serve. Let the tart rest for a few minutes before slicing. Finish with a drizzle of aged balsamic and fresh thyme. Cut the pastry into squares and serve.
Notes
- Keep the Puff Pastry Cold: Keep the thawed pastry cold for the flakiest, golden crust.
- Soften the Boursin: Let the cheese sit at room temperature for 30–60 minutes for easier spreading.
- Slice the Onions Thinly: Use a mandoline to slice the onions about ⅛ inch thick so they soften evenly.
- Storage and Reheating: Refrigerate cooled leftovers in an airtight, paper towel-lined container for up to 3 days. Reheat on a baking sheet at 325°F until warmed through and crisp.
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