This scalloped butternut squash gratin is made with caramelized onions, sage, garlic, and thyme in a creamy sauce, layered and topped with Parmesan cheese and breadcrumbs, then baked until golden and bubbling.

💡Recipe Overview
- Prep and Cook Time: 20 minutes to prep and 1 hour to bake
 - Cooking Method: Stove-top for cream sauce, then oven-baked
 - Dietary Info: Primal, GAPS, Ancestral diet
 - Tools Needed: Casserole dish
 - Skill Level: Moderate
 
What is an ancestral diet? Read my post on what nourishing foods are based on the traditional dietary principles of the Weston A. Price Foundation.
Reasons to Love this Butternut Squash Gratin
I used to think butternut squash was just ...fine. Nothing to get excited about. Then I tried this gratin, and I've been hooked ever since.
Tender, naturally sweet squash gets cozy with savory, creamy sauce that's basically begging to be devoured. It's the perfect mix of sweet and savory, rich but not heavy, and just plain delicious. And that pinch of nutmeg - chef's kiss!
Serve it alongside roast chicken, spatchcock turkey, or slow cooker duck - either way, it disappears fast.
One bite and you'll be rethinking everything you thought you knew about squash.

Ingredients for Butternut Squash Gratin

- Butternut squash – choose a firm, heavy squash with smooth skin. Peel, seed, and slice thinly (about ⅛ inch thick) for tender, evenly cooked layers.
 - Onion – caramelized onion adds natural sweetness and rich flavor depth.
 - Garlic – freshly minced garlic gives a savory, aromatic boost.
 - Butter – adds richness and helps caramelize the onions for a deeper, buttery flavor.
 - Fresh herbs – sage and thyme bring a warm, earthy flavor that pairs beautifully with squash. You can use dried but fresh herbs are abundant this time of year and it truly does make a difference in this gratin.
 - Heavy cream – makes a smooth, velvety sauce that binds the layers together.
 - Parmesan cheese – adds a salty, nutty flavor and helps form a golden, crisp topping.
 - Breadcrumbs – provide a light crunch on top; use gluten-free or omit if preferred.
 - Seasoning blend – a balanced mix of sea salt, black pepper, and a pinch of nutmeg enhances the cream sauce and highlights the sweetness of the squash.
 

Make it Ancestral
Use quality ingredients like fresh, locally grown butternut squash, grass-fed butter, and raw cream if accessible. Choose aged Parmesan for better digestibility and deeper flavor.

How to Make Butternut Squash Gratin
The complete printable recipe is below in the recipe card for your convenience. Follow these simple step-by-step instructions for the best results.

Step 1. Slice
Peel butternut squash and cut lengthwise. Remove seeds and pith. Thinly slice crosswise into ⅛-inch thick circles. You can also cut into half-moons.

Step 2. Saute
Melt butter in a large skillet over medium heat. Add sliced onions and season with salt to release juices. Cook until onions are caramelized (approximately 25 minutes), stirring occasionally.

Step 3. Add
Add garlic, sage leaves, thyme, and season with salt, pepper, and nutmeg and cook just until fragrant.

Step 4. Simmer
Reduce heat to medium-low and add heavy cream. Whisk to combine everything and cook until cream sauce has thickened.

Step 5. Layer
Spoon ¼ of the onion cream mixture to the bottom of the casserole dish. Arrange odds and ends of butternut squash slices across the dish, overlapping slightly. Spoon another ¼ of the cream onion mixture. Add a second layer of the butternut squash, followed by the 3rd ¼ of the onion cream mixture.

Step 6. Bake
Add the final layer of butternut squash, overlapping and pressing down so the top is flat all across the baking dish. Drizzle the remaining onion mixture. Spread the cream onion sauce evenly to cover the squash. Sprinkle with Parmesan cheese and breadcrumbs. Add extra sage leaves on top and bake for 40 minutes.
Helpful Tips
- Caramelize onions - stir onions occasionally but don't rush them; slow cooking develops deel flavor.
 - Slice thin and uniform - cut the butternut squash very thinly (⅛th of an inch) and as evenly as possible so it cooks consistently and layers neatly.
 - Use odds and ends first - place the irregular or smaller pieces on the bottom layer and reserve the most perfect half-moons for the top layer to make the gratin look appealing.
 - Brown the top - broil the last few minutes of cook time to brown and crisp the tops. But avoid overcooking the gratin so the squash doesn't become mushy but still has defined layers.
 

Serving Suggestions
I love serving this gratin at holidays as a fancy side dish but it will also work for any time of year.
Side dish: Serve this gratin with Yukon gold mashed potatoes or garlic green beans for an extra cozy, comforting meal.
Main dish: Pair this creamy butternut squash gratin with pork bites or rack of lamb for a hearty and satisfying dinner.
Fresh salads: Don’t forget to round out your meal with refreshing and vibrant salads. Romaine Salad and arugula salad are great options.
Condiments: Include probiotic-rich sides like fermented carrots or raw sauerkraut to add brightness and balance to the rich, creamy flavors.
More butternut squash gratin pairing suggestions:
- Crispy Pork Bites20 Minutes
 - Roasted Rack of Lamb with Garlic and Herb Crust50 Minutes
 - Chunky Mashed Potatoes with Red Skin30 Minutes
 - Chimichurri Chicken Thighs1 Hours 10 Minutes
 

Frequently Asked Questions
Gratin can be stored in an airtight container in the fridge for up to 4 days. Reheat in a 350°F (175°C) oven for 15-20 minutes until warmed through.
Yes, you can freeze it for up to 2 months; wrap tightly with plastic wrap and foil. Thaw in the refrigerator overnight and reheat in the oven, adding 5-10 extra minutes to ensure it is heated evenly.
Yes, but the sauce will be lighter and less rich. If you don't have heavy cream, I would use half-and-half but try to avoid using milk as the sauce will be too thin.
Looking for more related recipes? Here are some ideas:
Did you make this butternut squash gratin? Please leave a ⭐⭐⭐⭐⭐ recipe rating in the recipe card below and leave a review in the comments. Thank you!💚
Printable Recipe
Creamy Butternut Squash Gratin
Ingredients
- 1 butternut squash about 2 pounds
 - 4 tablespoons butter
 - 1 large onion sliced
 - 4 garlic cloves
 - 12 sage leaves cut into thin strips
 - 1 tablespoon fresh thyme leaves
 - 1 teaspoon sea salt
 - ½ teaspoon black pepper
 - ⅛ teaspoon nutmeg
 - 1 cup heavy cream
 - ½ cup grated Parmesan cheese
 - ¼ cup breadcrumbs
 
Instructions
- Preheat oven to 375°F. Peel 1 butternut squash and cut lengthwise. Remove seeds and pith. Thinly slice crosswise into ⅛-inch thick circles. You can also cut into half-moons.
 - Melt 4 tablespoons butter in a large skillet over medium heat. Add sliced 1 large onion sliced and season with salt to release juices. Cook until onions are caramelized (approximately 25 minutes), stirring occasionally.
 - Add 4 garlic cloves, 12 sage leaves, 1 tablespoon fresh thyme leaves, and season with 1 teaspoon sea salt, ½ teaspoon black pepper, and ⅛ teaspoon nutmeg and cook just until fragrant.
 - Reduce heat to medium-low and add 1 cup heavy cream. Whisk to combine everything and cook until cream sauce has thickened.
 - Spoon ¼ of the onion cream mixture to the bottom of the casserole dish. Arrange odds and ends of butternut squash slices across the dish, overlapping slightly. Spoon another ¼ of the cream onion mixture. Add a second layer of the butternut squash, followed by the 3rd ¼ of the onion cream mixture. Add the final layer of butternut squash, overlapping and pressing down so the top is flat all across the baking dish. Drizzle the remaining onion mixture.
 - Spread the cream onion sauce evenly to cover the squash. Sprinkle with ½ cup grated Parmesan cheese and ¼ cup breadcrumbs. Add extra sage leaves on top.
 - Cover with a piece of parchment paper then aluminum foil. Bake covered for 40 minutes on the middle rack. Remove the cover and bake for 10 more minutes to brown the tops. Remove from oven and allow to rest for 5 minutes for sauce to settle before serving.
 
Video
Notes
- Caramelize onions - stir onions occasionally but don't rush them; slow cooking develops deel flavor.
 - Slice thin and uniform - cut the butternut squash very thinly (⅛th of an inch) and as evenly as possible so it cooks consistently and layers neatly.
 - Use odds and ends first - place the irregular or smaller pieces on the bottom layer and reserve the most perfect half-moons for the top layer to make the gratin look appealing.
 - Brown the top - broil the last few minutes of cook time to brown and crisp the tops
 




















































































