This mini Butternut Squash Gratin is the perfect fall and winter side dish to add to your holiday menu or weeknight dinner with any protein. It’s rich, creamy and easy to make as well as prepare ahead of time for dinnertime ease.
This Butternut Squash Gratin is a great side dish for fall and winter. Layers of tender Butternut squash are baked until soft with a golden top that adds a little texture to every bite. It’s the perfect size for 1–2 servings, making it a great option for a smaller holiday gathering or a weeknight dinner.
I love finding new ways to use seasonal squash, especially around Thanksgiving when I’m always looking for ways to switch up the usual sides. Butternut squash is one of my favorites because it’s smaller and sweeter than butternut squash, making it perfect for a gratin. I especially love that this recipe is made in a smaller portion, so you can enjoy a holiday-inspired side without making a full casserole.
If you love this side dish, you’ll love my Sweet Potato Tart and my Cocotte French Potatoes.
Why You’ll Love This Recipe
- Perfect for fall and winter: Butternut squash is in season during the colder months, making this a great side dish for Thanksgiving or holiday dinners.
- Great texture: The squash becomes tender as it bakes, while the golden top adds a little texture to every bite.
- Perfect for 1–2 servings: This smaller gratin is ideal when you’re cooking for one or two people and don’t want to make a full casserole.
- A twist on a classic gratin: Using honeynut or butternut squash instead of potatoes adds natural sweetness and a seasonal spin to a traditional side dish.
- Easy to serve: The smaller portion makes it a great option for weeknight dinners or adding an extra side to your holiday menu.
Ingredients
- Butternut Squash: Adds a naturally sweet, nutty flavor and becomes tender as it bakes, pairing well with the creamy Boursin sauce and caramelized onions.
- Butter: Used to caramelize the onions and create the base of the creamy Boursin cream sauce.
- Heavy Cream: Adds richness to the Boursin cream sauce and helps create a creamy texture throughout the gratin.
- Boursin Cheese: Adds a creamy texture and garlic and herb flavor to the cream sauce.
- Gruyère Cheese: Melts into the gratin and creates a golden, bubbly cheese topping when baked.
- Thyme: Fresh thyme adds an earthy, herbal flavor that pairs well with the sweetness of the squash.
- Nutmeg: A pinch of nutmeg adds warmth to the cream sauce and complements the cream and cheese.
- Chives: Fresh chopped chives add a mild onion flavor and a little freshness when sprinkled over the finished gratin.
- Yellow Onion: Slowly caramelized in butter until soft and golden, yellow onions add a layer of sweetness between the squash and creamy sauce.
How to Make Butternut Squash Gratin
1. Prepare the Butternut squash: Preheat the oven to 375°F. Peel the butternut squash, cut it in half lengthwise, and scoop out the seeds. Using a mandoline or sharp knife, slice the squash into thin, even slices, approximately ⅛ inch thick.
2. Caramelize the onions: Melt 1 tablespoon of butter in a skillet over medium-low heat. Add the thinly sliced yellow onion and a pinch of salt. Cook for 20–25 minutes, stirring occasionally, until the onions are soft, golden brown, and caramelized. Reduce the heat if the onions begin to brown too quickly, adding a splash of water as needed to prevent sticking. Remove from the heat and set aside.
3. Make the Boursin cream sauce: In a small saucepan over low heat, melt 1 tablespoon of butter. Stir in heavy cream and Boursin cheese. Stir until smooth and the sauce begins to thicken, about 2 minutes. Add the nutmeg, salt, and black pepper.
4. Prepare the cocotte: Butter the inside of a 24 oz cocotte, coating the bottom and sides. Add a few leaves of fresh thyme along the bottom and sides of the cocotte.
5. Layer the squash and caramelized onions: Arrange a layer of thinly sliced butternut squash over the thyme, slightly overlapping the slices. Season lightly with salt and pepper. Add a thin layer of caramelized onions over the squash. Repeat the layers of squash and onions until the cocotte is nearly full, finishing with a layer of squash.
6. Add the Boursin cream sauce and Gruyère: Slowly pour the Boursin cream sauce evenly over the layered squash, allowing it to settle into the spaces between the slices. Gently tap the cocotte on the counter to help distribute the sauce. Sprinkle the freshly grated Gruyère cheese evenly over the top.
7. Bake the gratin: Cover the cocotte and bake at 375°F for 20 minutes. Remove the lid and bake for another 20 minutes, or until the squash is tender and the cheese is golden. Finish under the broiler for 2–3 minutes until the top is bubbling and browned, watching closely to prevent burning. Remove and top with chopped chives. Enjoy!
Expert Tips
- Slice the squash evenly: Cut the butternut squash into thin, uniform slices to ensure it cooks evenly and becomes tender throughout.
- Avoid a watery gratin: Make sure the cream sauce is slightly thickened before pouring it over the squash, and avoid adding excess liquid.
- Test the center for tenderness: Insert a knife into the center of the gratin to make sure the squash is fully cooked before removing it from the oven.
- Let it rest before serving: Allow the gratin to rest for 5–10 minutes after baking so the sauce can thicken and the layers can set.
Variations & Substitutions
- Try different dairy: Swap the heavy cream for half-and-half or whole milk for a lighter cream sauce, keeping in mind the texture may be slightly less rich.
- Add another cheese: Try adding Parmesan, sharp cheddar or fontina alongside the Gruyère for a different flavor and extra cheesiness.
- Experiment with herbs and spices: Fresh sage, rosemary or a pinch of cayenne pepper are great additions that complement the sweetness of the butternut squash.
- Top with breadcrumbs: Sprinkle panko breadcrumbs tossed with melted butter over the gratin before baking uncovered for an extra crispy topping.
- Use honeynut squash: Swap butternut squash for thinly sliced butternut squash, using just enough to fill the cocotte and adjusting the baking time as needed.
What to Serve With Butternut Squash Gratin
- Brown Butter and Sage Popovers
- Goat Cheese Bacon Wrapped Dates
Rosemary Citrus Roast Chicken
Chicory Salad with a Pancetta Shallot Vinaigrette
Green Bean Casserole Puff Pastries
Storage
Fridge: Store leftover butternut squash gratin in an airtight container in the refrigerator for up to 3–4 days. Reheat in a 350°F oven until warmed through, uncovering toward the end to help crisp the cheese topping.
Freezer: Freezing is not recommended because the Boursin cream sauce can separate when thawed and the squash may become watery, affecting the texture of the gratin.
Make Ahead: Caramelize the onions and prepare the Boursin béchamel up to 2 days in advance, storing them separately in the refrigerator. You can also assemble the gratin up to 24 hours ahead and refrigerate it covered until ready to bake, allowing a little extra baking time if cooking straight from the fridge.
FAQs
Yes, I recommend peeling butternut squash before making this gratin, as the skin is tougher than honeynut squash and can affect the texture of the finished dish.
Yes, you can assemble the gratin up to 24 hours in advance and store it covered in the refrigerator until ready to bake. You may need to add a few extra minutes to the baking time if it’s going straight from the fridge to the oven.
If your squash is still firm, the slices may be too thick or the gratin may need more time in the oven. Cover and continue baking until a knife slides easily through the center of the squash.
Yes, thinly sliced sweet potatoes are a great substitute for butternut squash and pair well with the Boursin cream sauce and caramelized onions. Keep the slices uniform and adjust the baking time as needed until tender.
More Easy Fall Recipes
- Butternut Squash Crostinis
- Sweet Potato Dip with Garlic Confit
Caramelized Apple, Onion, and Cheddar Tart
Cinnamon Butter & Hot Honey Apple Crostinis
Butternut Squash Gratin
Equipment
- 1 24 oz cocotte
Ingredients
For the gratin:
- 1 medium butternut squash peeled and thinly sliced (about 1½–2 cups)
- 1 small yellow onion thinly sliced
- 1 tablespoon unsalted butter for caramelizing the onions
- 1 teaspoon butter for greasing the cocotte
- 2 sprigs fresh thyme
- ⅓ cup freshly grated Gruyère cheese
- 1 tablespoon fresh chives finely chopped
- Salt and freshly cracked black pepper to taste
For the Boursin cream sauce:
- ½ cup heavy cream
- ¼ cup Boursin Garlic & Fine Herbs cheese
- ⅛ teaspoon ground nutmeg
- Salt and freshly cracked black pepper to taste
Instructions
- Prepare the butternut squash: Preheat the oven to 375°F. Peel the butternut squash, cut it in half lengthwise, and scoop out the seeds. Using a mandoline or sharp knife, slice the squash into thin, even slices, approximately ⅛ inch thick.
- Caramelize the onions: Melt 1 tablespoon of butter in a skillet over medium-low heat. Add the thinly sliced yellow onion and a pinch of salt. Cook for 20–25 minutes, stirring occasionally, until the onions are soft, golden brown, and caramelized. Reduce the heat if the onions begin to brown too quickly, adding a splash of water as needed to prevent sticking. Remove from the heat and set aside.
- Make the Boursin cream sauce: In a small saucepan over low heat, melt 1 tablespoon of butter. Stir in heavy cream and Boursin cheese. Stir until smooth and the sauce begins to thicken, about 2 minutes. Add the nutmeg, salt, and black pepper.
- Prep the cocotte: Butter the inside of a 24 oz cocotte, coating the bottom and sides. Add a few leaves of fresh thyme along the bottom and sides of the cocotte.
- Layer the squash and caramelized onions: Arrange a layer of thinly sliced butternut squash over the thyme, slightly overlapping the slices. Season lightly with salt and pepper. Add a thin layer of caramelized onions over the squash. Repeat the layers of squash and onions until the cocotte is nearly full, finishing with a layer of squash.
- Add the Boursin cream sauce and Gruyère: Slowly pour the Boursin cream sauce evenly over the layered squash, allowing it to settle into the spaces between the slices. Gently tap the cocotte on the counter to help distribute the sauce. Sprinkle the freshly grated Gruyère cheese evenly over the top.
- Bake the gratin: Cover the cocotte and bake at 375°F for 20 minutes. Remove the lid and bake for another 20 minutes, or until the squash is tender and the cheese is golden. Finish under the broiler for 2–3 minutes until the top is bubbling and browned, watching closely to prevent burning. Remove and top with chopped chives. Enjoy!
Video
Notes
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