Butternut Squash Tart (Butternut Squash Recipe)

A rustic butternut squash recipe featuring squash prepared two ways, plus caramelized onions, sautéed spinach, fresh herbs, and two kinds of cheese, all layered on a flaky puff pastry base.

What Inspired This Butternut Squash Recipe?

Along with cranberry, ginger, apple, and pear, butternut squash is one of those flavors that simply screams autumn. As the days grow shorter and the air turns crisp, I find myself introducing more of all of these ingredients (plus plenty of chai, cinnamon, and pumpkin spice, of course!) into my cooking and baking projects.

Butternut squash tastes great in its most basic form, roasted in oil or butter, along with salt, pepper, and maybe a touch of brown sugar. It also makes a unique addition to soups and stews, along with sweet recipes like pancakes, muffins, puddings, and pies.

Layered on a puff pastry base, this butternut squash recipe features two squash preparation (a spiced puréed sauce, and a roasted squash topping), plus caramelized onions, sautéed spinach, fresh herbs, and two kinds of cheese. Like butternut squash itself, the finished product is highly adapatable—this tart works for brunch, lunch, or a light dinner. Serve it alone, pair it with a bowl of homemade soup, or slice and arrange on a tray with other puff pastry appetiziers like pineapple pizza rolls; pesto pinwheels; and cheese and Marmite twists.

Butternut Squash Tart Recipe Ingredients

To make this butternut squash recipe, you’ll need the following ingredients:

• Unsalted Butter – For caramelizing the onions.
• White Onions – 300 grams, or about 2 medium onions, peeled and sliced into very thin rings.
• Butternut Squash – This recipe requires a total of about 400 grams (14 ounces, or about 3 1/3 US cups) of peeled and diced butternut squash. Half of this you’ll boil and purée to create the sauce (if you’ve made my butternut squash pudding, you’ll employ the same technique here.) The rest you’ll sautée for the topping. For squash preparation tips, see my notes below.
• Herbs and Spices – You’ll need one cinnamon stick for simmering the squash (cinnamon usually comes in big bags, so save the rest for hot buttered brandy or a vanilla chai simmer pot!), plus chili flakes, chopped fresh rosemary, and kosher salt and ground black pepper, to taste.
• Olive Oil – For sautéeing the cubed squash. You can use a standard extra virgin olive oil, or substitute rosemary infused oil for a more herb-forward tart.

• Spinach – I used 80 grams (about 2 3/4 ounces or 4 US cups) of raw spinach. I recommend baby spinach leaves—they’re tender, and less chewy than the larger leaves.
• Puff Pastry – You can use homemade puff pastry if you enjoy making your own, but I make most of my puff pastry tarts with store-bought pasty. If using frozen rather than refrigerated, allow plenty of time for the pastry to thaw according to the manufacturer’s instructions.
• Cheeses – I topped my tart with a combination of blue cheese and Parmesan. If you don’t like blue cheese, replace it with feta, goat cheese, or another cheese of your choice.
• Egg – Lightly beaten, to egg wash the pastry. You can use the whole egg, or the yolk only for a deeper brown color.

Caramelizing the Onions

If you’ve never made caramelized onions from scratch, you’ll quickly discover that this staple kitchen technique doesn’t take much effort, but it does require a decent chunk of time. (You’ll frequently hear the term “low and slow” in relation to caramelizing onions, and for good reason!) I suggest allowing at least one hour to fully caramelize the onions.

To do so, simply melt the butter in a saucepan, add the onion rings, and cook over very low heat, stirring occasionally with a spatula, until the onions turn soft, jammy, and deeply golden brown:

Once you get the hang of caramelizing onions, you can use the same technique to make the onions for my fig and goat cheese tart and my lattice pastry with cheese and caramelized onions, too.

Preparing the Butternut Squash

You’ll need about 400 grams, or about 3 1/3 cups, of peeled and diced butternut squash.

I’ll admit that butternut squash is one of the few ingredients where I’m willing to pay extra for convenience, and will usually purchase already-peeled-and-cubed squash. In most US and UK supermarkets, you’ll find pre-diced butternut squash in the refrigerated section of the produce department—it usually comes in a bag or a clear plastic container.

If you do want to start with a whole butternut squash, I recommend popping it in the microwave for a few minutes. This trick softens the skin, making the squash much easier to slice.

Puff Pastry Tart Recipe Tips and Tricks

Go with the flow. This butternut squash recipe is meant to be rustic, so don’t worry about sticking to a specific size or shape. If your puff pastry is a few inches bigger or smaller than mine, just go with it! If you want, you can even make a square-shaped tart, or trace around a dinner plate to make a round butternut squash galette.

Start with parchment. Cover your tray with a sheet of parchment, then assemble the tart on top. Do not try to make this tart directly on the countertop, or you’ll risk damage when you transfer it to the baking tray.

Aim for smooth purée. After puréeing the cooked squash, check to make sure that no visible clumps or chunks remain. If necessary, pass the purée through a fine mesh strainer before spreading it on the pastry base.

Use a sharp knife. You’ll need a sharp chef’s knife, pizza cutter, or kitchen shears to cut and serve the tart. You can slice the rectangle into 4-6 larger squares for dinner, or tinier pieces for appetizer-sized portions.

Egg wash with care. When applying the egg wash, do your best to brush the flat parts of the pastry only, rather than the thin edges, which can cause the layers to stick together and prevent pastry from “puffing” as much as it bakes.

Make-Ahead and Storage Suggestions

You can caramelize the onions and prepare the butternut squash purée up to 24 hours in advance. Refrigerate in airtight containers until you’re ready to assemble the tart.

Wrap leftover tart in foil and refrigerate for up to 2 days. Eat cold or gently rewarm in a 350° F / 176° C oven for 10 minutes, or until warmed through. I do not suggest reheating puff pastry in the microwave.

Other savory puff pastry tarts you might enjoy:

Asparagus Puff Pastry Tart
Fig and Goat Cheese Tart
Rustic Tomato Tart
Rainbow Veggie Pizza
Lattice Pastry with Cheese and Caramelized Onions

And if you do make these, or any of my recipes, don’t forget to tag me @bastecutfold or use the hashtag #bastecutfold on Instagram. I always love to see what you’re making!

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