Caramelized Onion Butternut Squash Tart

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Sweet, savory, and utterly comforting, this Caramelized Onion Butternut Squash Tart is the kind of cozy recipe that brings elegance to a weekday dinner or a festive touch to a holiday table. With its buttery crust, golden roasted butternut squash, rich caramelized onions, and a sprinkle of tangy blue cheese, every bite is an irresistible balance of flavor and texture.

Perfect as a vegetarian main course or an eye-catching side dish, this tart is layered with deeply savory notes and warm, nutty undertones. It’s hearty without being heavy and works just as beautifully with a crisp salad as it does alongside a roast.

Why You’ll Love This Caramelized Onion Butternut Squash Tart

• It features rich, slow-cooked caramelized onions for a sweet-savory base.
• Butternut squash brings color, depth, and a natural earthy sweetness.
• The flaky crust holds everything together beautifully.
• A touch of blue cheese gives it a sophisticated edge.
• It’s make-ahead friendly and perfect for entertaining.

What Kind of Crust Should I Use?

A classic buttery tart crust works best for this recipe. You can make your own shortcrust pastry or use a high-quality store-bought one. Just make sure it’s blind-baked to avoid a soggy bottom. For extra flavor, try adding a pinch of dried thyme or grated Parmesan to the dough.

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Ingredients

• Butternut squash: Roasted for natural sweetness and creamy texture.
• Yellow onions: Slowly caramelized to develop deep, sweet flavor.
• Olive oil: Used to roast the squash and cook the onions.
• Butter: Adds richness to the onions while they cook.
• Fresh thyme: Adds earthy, aromatic notes that pair beautifully with the squash.
• Eggs: Bind the filling and give it structure.
• Heavy cream: Creates a custardy texture in the tart.
• Blue cheese: Crumbled on top for a sharp, tangy contrast.
• Salt and black pepper: Enhances all the other flavors.
• Tart crust (homemade or store-bought): The crisp and buttery foundation for the tart.

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How To Make the Caramelized Onion Butternut Squash Tart

Step 1: Roast the Butternut Squash

Preheat your oven to 400°F (200°C). Peel and cube the butternut squash, then toss with olive oil, salt, pepper, and fresh thyme. Spread on a baking sheet and roast for 25 minutes, or until tender and lightly browned.

Step 2: Caramelize the Onions

While the squash roasts, thinly slice the onions. Heat a large skillet over medium-low heat and add olive oil and butter. Cook the onions slowly, stirring often, for 30-40 minutes until deep golden and caramelized.

Step 3: Blind Bake the Tart Crust

If using a homemade or store-bought crust, press it into a tart pan and prick the bottom with a fork. Line with parchment paper and fill with baking weights. Bake at 375°F (190°C) for 15 minutes, then remove the weights and bake another 10 minutes until lightly golden.

Step 4: Prepare the Filling

In a large bowl, whisk together eggs, heavy cream, salt, and pepper. Stir in half the caramelized onions and half the roasted squash.

Step 5: Assemble and Bake

Pour the filling into the baked crust. Top with the remaining onions and squash, and sprinkle with crumbled blue cheese. Bake at 375°F (190°C) for 30-35 minutes until the center is set.

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How to Serve This Tart Beautifully (Serves 6)

Serve warm or at room temperature with a light salad or roasted vegetables. It makes a stunning vegetarian main dish or a flavorful side for grilled meats or holiday roasts. A drizzle of balsamic glaze or a spoonful of cranberry chutney can add a sweet-tart contrast.

Best Ways to Store the Tart

Let the tart cool completely before storing. Cover tightly and refrigerate for up to 3 days. To reheat, warm slices in a 325°F (165°C) oven until heated through. This tart also freezes well: wrap tightly in plastic and foil, and freeze for up to 1 month. Reheat from frozen at 350°F (175°C).

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Frequently Asked Questions

Can I use a different cheese?
Absolutely. Goat cheese or feta can replace blue cheese if you prefer a milder tang.

What if I don’t have a tart pan?
Use a pie dish, but reduce the filling slightly so it doesn’t overflow.

Can I make it dairy-free?
Yes. Use plant-based cream and omit the cheese or substitute with a dairy-free version.

Do I have to caramelize the onions?
Yes, it’s essential for the flavor. But you can prep them ahead of time and refrigerate until needed.

Can I make this tart ahead?
Definitely. Bake the full tart, cool it, and refrigerate. Reheat before serving.

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Want More Tart and Veggie-Based Ideas?

If you loved this savory tart, you might enjoy these too:

• Creamy Baked Onions with Asiago Cheese
• Root Veggie Gratin
• Garlic Parmesan Potato Wedges
• Roasted Pumpkin with Lemon Yogurt & Pine Nuts
• Rustic Garlic Rosemary Skillet Bread

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📌 Save this recipe to your Pinterest dinner board so you can come back to it any time.

And let me know in the comments how yours turned out. Did you swap the cheese or spice it up with chili flakes? I love hearing your twists. Questions welcome too—let’s make it even better together.

For more savory and seasonal inspiration, check out my collection on Life With Livia.

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