Caramelized Onion Butternut Squash Tart

This Caramelized Onion Butternut Squash Tart combines golden roasted squash, slowly caramelized onions, tangy goat cheese, fresh thyme, and crisp puff pastry in one easy-to-slice tart. The squash becomes tender and lightly sweet in the oven, while the onions cook low and slow until soft, jammy, and deeply golden.

It looks special enough for a holiday appetizer or brunch table, but the ingredients are simple enough for a relaxed weekend lunch or dinner. You can prepare the onions and squash ahead, then assemble and bake the tart when you’re ready to eat. A little balsamic vinegar at the end balances the sweetness, while the flaky pastry gives every bite a crisp, buttery base.

Quick Recipe Snapshot

Why You’ll Want to Make This

• Beautiful without complicated pastry work: Store-bought puff pastry keeps the preparation simple.
• Full of contrasting flavors: Sweet squash and onions pair with tangy goat cheese and balsamic vinegar.
• Great for fall gatherings: It makes an attractive centerpiece for a brunch or holiday appetizer spread.
• Easy to prepare ahead: The squash and onions can be cooked before assembly.
• Flexible: You can change the cheese, herbs, or toppings depending on what you have.
• Good for leftovers: The tart reheats well in the oven, especially when you want the pastry crisp again.

Ingredients

For the Tart

• 1 sheet puff pastry, thawed according to package directions
• 2 cups butternut squash, peeled, seeded, and cut into ½-inch cubes
• 2 medium yellow onions, thinly sliced
• 2 tablespoons olive oil, divided
• 1 tablespoon unsalted butter
• 1 teaspoon fresh thyme leaves, plus extra for topping
• ½ teaspoon kosher salt, divided
• ¼ teaspoon black pepper
• 1 teaspoon maple syrup
• 1 teaspoon balsamic vinegar
• 4 ounces goat cheese, softened and crumbled
• 1 egg, beaten, for brushing the pastry
• 1 tablespoon water, mixed with the beaten egg

Optional Garnish

• 1 tablespoon chopped fresh parsley
• A few extra fresh thyme leaves
• 1 teaspoon balsamic glaze, for drizzling

Ingredient Notes

Butternut Squash

Fresh butternut squash gives the tart a sweet, roasted flavor and soft texture. Cut the cubes fairly small so they cook quickly and are easy to arrange over the pastry.

Shortcut: Pre-cut refrigerated butternut squash works well.

Onions

Yellow onions are ideal because they become soft and sweet as they caramelize. Slice them thinly and evenly so they cook at the same rate.

Puff Pastry

Use one standard sheet of thawed puff pastry. Keep it cold while you prepare the filling. If the pastry becomes very soft, place it in the refrigerator for 10–15 minutes before assembling the tart.

Goat Cheese

Goat cheese adds tang and creaminess that balances the sweetness of the squash and onions.

Substitution: Crumbled feta works if you prefer a firmer, saltier cheese.

Maple Syrup

Just one teaspoon adds a subtle sweetness to the roasted squash. It isn’t meant to make the tart taste like dessert.

Balsamic Vinegar

A small amount adds acidity and keeps the finished tart from tasting overly sweet.

How to Make Caramelized Onion Butternut Squash Tart

1. Roast the Butternut Squash

Preheat the oven to 400°F (200°C).

Line a large baking sheet with parchment paper.

Place the cubed butternut squash on the baking sheet. Add 1 tablespoon olive oil, ¼ teaspoon salt, and the black pepper. Toss until the squash is evenly coated.

Spread the squash into a single layer.

Roast for 20–25 minutes, turning once halfway through. The squash should be tender when pierced with a fork and lightly browned around the edges.

Remove from the oven and set aside.

Tip: Don’t pile the squash together. A little space between the pieces helps them roast instead of steam.

2. Caramelize the Onions

While the squash roasts, heat the remaining 1 tablespoon olive oil and the butter in a large skillet over medium-low heat.

Add the sliced onions and the remaining ¼ teaspoon salt.

Cook for 25–30 minutes, stirring every few minutes.

The onions will first soften and become translucent. Continue cooking until they turn deep golden brown and jammy.

If the onions start sticking or browning too quickly, lower the heat and add 1 tablespoon of water. Scrape the bottom of the pan and continue cooking.

Once caramelized, stir in the balsamic vinegar and cook for about 30 seconds.

Remove from the heat.

3. Prepare the Puff Pastry

Keep the oven at 400°F (200°C).

Place the thawed puff pastry on a parchment-lined baking sheet.

Using a sharp knife, lightly score a border about ¾ inch from the edge of the pastry. Don’t cut all the way through.

Prick the center area several times with a fork, leaving the border untouched.

This helps the outer edge puff while the center stays relatively flat for the toppings.

4. Add the Filling

Spread the caramelized onions over the center of the pastry, staying inside the scored border.

Scatter the roasted butternut squash evenly over the onions.

Sprinkle the goat cheese over the top.

Drizzle the squash and cheese with the 1 teaspoon maple syrup, then sprinkle with fresh thyme.

5. Brush the Pastry

Whisk together the beaten egg and 1 tablespoon water.

Brush the egg wash over the exposed pastry border.

Try not to let the egg wash run over the cut edges of the pastry, as this can interfere with how it puffs.

6. Bake the Tart

Bake at 400°F (200°C) for 22–25 minutes.

The pastry should be puffed and golden brown, and the bottom should look crisp rather than pale or doughy.

If the edges are browning too quickly before the center is crisp, loosely cover the edges with foil during the final few minutes.

7. Rest and Serve

Let the tart cool on the baking sheet for 5–10 minutes.

Scatter with extra fresh thyme and parsley if using.

For a sharper finish, drizzle lightly with balsamic glaze.

Cut into squares or strips and serve warm.

Recipe Tips

Keep the puff pastry cold

Cold pastry gives you better puff and a flakier texture. If it becomes soft while you’re assembling the tart, refrigerate it briefly.

Don’t rush the onions

The onions are one of the main flavor components. Medium-low heat gives them time to become soft and deeply golden without burning.

Cut the squash evenly

½-inch cubes are small enough to become tender before the tart finishes baking.

Roast instead of steaming

Give the squash room on the baking sheet. Crowding traps moisture and makes it harder to get browned edges.

Don’t overload the pastry

A thick layer of filling can make the center soggy. Keep the toppings fairly even and stay inside the pastry border.

Let the tart rest

A short rest makes the tart easier to cut and gives the cheese and filling time to settle.

Bake on a metal sheet

A metal baking sheet helps the bottom of the puff pastry become crisp.

Serve warm

The tart is best while the pastry is still crisp and the cheese is soft.

Variations & Substitutions

Use Feta Instead of Goat Cheese

Replace the goat cheese with 4 ounces crumbled feta for a saltier, more pronounced flavor.

Add Fresh Sage

Replace some or all of the thyme with chopped fresh sage. Sage pairs especially well with roasted butternut squash.

Add Walnuts

Scatter ¼ cup toasted chopped walnuts over the finished tart for crunch.

Make It Dairy-Free

Use a dairy-free puff pastry and replace the butter with another tablespoon of olive oil. Use a suitable dairy-free cheese or leave the cheese out.

Add Greens

Add a small handful of baby spinach to the caramelized onions during the final 1–2 minutes of cooking. Let excess moisture cook away before assembling the tart.

Add Chili Flakes

For a little heat, sprinkle ¼ teaspoon red pepper flakes over the squash before assembling the tart.

What to Serve With It

Simple Green Salad

A lemony green salad adds freshness and acidity alongside the rich pastry.

Roasted Brussels Sprouts

Their roasted edges work naturally with the caramelized onion and squash.

Tomato or Cucumber Salad

A fresh salad adds a lighter contrast to the warm tart.

Creamy Soup

Serve a small bowl of tomato, mushroom, or cauliflower soup alongside the tart for a cozy lunch.

Apple and Arugula Salad

Thinly sliced apple, peppery arugula, and a simple vinaigrette complement the sweet squash.

Holiday Appetizer Board

Cut the tart into small squares and serve it alongside olives, nuts, fruit, and other appetizers.

Make-Ahead, Storage & Reheating

Can I Make It Ahead?

Yes. The roasted squash and caramelized onions can be prepared up to 2 days ahead. Refrigerate them separately in airtight containers.

When you’re ready to bake, assemble the tart with the chilled filling and bake as directed.

How to Store Leftovers

Let the tart cool completely, then refrigerate it in an airtight container for up to 3 days.

How to Reheat

For the crispiest pastry, reheat slices in a 375°F (190°C) oven for about 8–12 minutes.

An air fryer can also work well. Reheat individual slices at 350°F (175°C) for about 4–6 minutes, checking early.

Avoid microwaving when possible because it softens the pastry.

Can I Freeze It?

You can freeze baked slices, although the pastry may lose some of its original crispness. Cool completely, wrap individual portions well, and freeze for up to 1 month.

Reheat directly from frozen in a 375°F (190°C) oven until hot and crisp.

Caramelized Onion Butternut Squash Tart

Recipe by Emily Carter

0.0 from 0 votes

Cuisine: French-InspiredDifficulty: Medium

Servings

6

servings

Prep time

25

minutes

Cooking time

55

minutes

Calories

290

kcal

Total time

1

hour 

20

minutes

Flaky puff pastry topped with roasted butternut squash, deeply caramelized onions, and creamy goat cheese — an elegant, easy tart perfect for fall gatherings.

Ingredients

• 1 sheet puff pastry, thawed

• 2 cups butternut squash, peeled, seeded, cut into ½-inch cubes

• 2 medium yellow onions, thinly sliced

• 2 tablespoons olive oil, divided

• 1 tablespoon unsalted butter

• 1 teaspoon fresh thyme leaves, plus extra for topping

• ½ teaspoon kosher salt, divided

• ¼ teaspoon black pepper

• 1 teaspoon maple syrup

• 1 teaspoon balsamic vinegar

• 4 ounces goat cheese, softened and crumbled

• 1 egg, beaten

• 1 tablespoon water, mixed with the egg

• 1 tablespoon chopped fresh parsley (optional garnish)

• Extra fresh thyme leaves (optional garnish)

• 1 teaspoon balsamic glaze, for drizzling (optional)

Directions

• Toss squash with 1 tablespoon oil, ¼ teaspoon salt, and pepper. Roast at 400°F for 20-25 minutes until tender and browned.
• Cook onions in remaining oil and butter with ¼ teaspoon salt over medium-low heat for 25-30 minutes until deeply caramelized. Stir in balsamic vinegar.
• Score a border on the puff pastry, prick the center with a fork, and keep it cold.
• Layer caramelized onions, roasted squash, and goat cheese inside the border. Drizzle with maple syrup and sprinkle with thyme.
• Brush the pastry border with egg wash (beaten egg + water).
• Bake at 400°F for 22-25 minutes until puffed and golden.
• Rest 5-10 minutes, garnish with thyme, parsley, and balsamic glaze. Slice and serve warm.

FAQs

Can I use pre-cut butternut squash?

Yes. Pre-cut refrigerated squash is a convenient option. Cut any larger pieces into roughly ½-inch cubes so everything roasts evenly.

Can I use frozen butternut squash?

Yes, but thaw it first and pat it very dry. Frozen squash contains more moisture, so drying it well helps prevent a soggy tart.

Can I make the caramelized onions ahead?

Absolutely. They can be cooked up to 2 days ahead and refrigerated. Bring them out when you’re ready to assemble the tart.

Can I use a different cheese?

Yes. Feta is an easy substitute. You could also use a small amount of shredded Gruyère or sharp white cheddar.

Why is my puff pastry soggy in the middle?

Too much moisture or too much filling can cause this. Make sure the squash is well roasted, the onions aren’t watery, and the toppings are spread in a fairly thin layer.

Can I make this tart without goat cheese?

Yes. You can use feta, another cheese you enjoy, or omit the cheese. The caramelized onions and squash will still provide plenty of flavor.

Can I serve this at room temperature?

Yes. It’s particularly convenient for a brunch or appetizer table when you don’t want to serve everything straight from the oven. For the crispest pastry, though, serve it warm.

Can I make smaller appetizer portions?

Yes. Cut the baked tart into small squares or strips after it has rested. For individual tarts, divide the puff pastry into smaller rectangles and reduce the baking time slightly, checking for a golden, crisp pastry.