Butternut Squash Lasagna

A close-up of a cheesy layered casserole with golden-brown edges, melted cheese, visible herbs, and a serving being lifted out with a spatula.

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This Butternut Squash Lasagna is the vegetarian main dish of my dreams! Layers of noodles, roasted squash, buttery spinach, a rich and savory cream sauce, and of course lots of Parmesan cheese make this the fall casserole that will steal the show this Thanksgiving. Delicious and hearty, it's the perfect comfort food on a chilly winter day. It's the perfect side dish OR main dish on Thanksgiving!

Prep Time50

Cook Time40

Total Time1 30

Course: Main Course

Cuisine: American

Servings:

Calories: 384kcal

Author: The Food Charlatan

Equipment

2 sheet pans for roasting the squash
1 9x13 baking dish for the lasagna

Ingredients

For the squash:

3 pounds butternut squash about 8 cups, chopped
1 and 1/2 teaspoons kosher salt divided, for roasting squash
3 tablespoons light olive oil divided, for roasting squash

For the spinach layer

4 tablespoons butter half stick
10 ounces fresh spinach*
3/4 teaspoon kosher salt

For the cream sauce

4 tablespoons butter half stick
5 cloves garlic smashed and minced (at least 1 tablespoon)
1/4 cup flour
1 teaspoon kosher salt
1/2 teaspoon black pepper
1 pinch cayenne pepper
1/4 teaspoon nutmeg
1 tablespoon fresh sage chopped
1 tablespoon fresh rosemary chopped
4 cups whole milk

For the lasagna

9 sheets no-boil lasagna noodles
1 and 1/2 cups shredded Parmesan cheese divided
1 cup whipping cream
1/2 teaspoon kosher salt
1/2 teaspoon pepper

Instructions

Preheat your oven to 450 degrees F.
Chop your butternut squash. I have a whole post dedicated to walking you through this because squash chopping can be a little intimidating! Tap to see the post.
Roast the squash. Spread 3 pounds of chopped butternut squash on TWO half sheet pans. Drizzle EACH pan with 3/4 teaspoon kosher salt and 1 and 1/2 tablespoons light olive oil, or any vegetable oil. Use your hands to toss the squash with the salt and oil, then spread all the chopped squash out on the pan, trying to make sure the squash pieces are not touching.
Roast at 450 F for 30 minutes, stopping to rotate the pans placement in the oven halfway. When the butternut is fork-tender, it's ready to go. Set aside for now.
Lower the oven temperature to 375.
Wilt the spinach. While the butternut roasts, melt 4 tablespoons butter in a large skillet over medium heat. Add 10 ounces fresh spinach.* Sprinkle with 3/4 teaspoon kosher salt. Cook for 2-4 minutes, until the spinach is wilted. Remove to a paper-towel lined plate, leaving any liquid in the pan.
Work ahead: Get your chopping out of the way before you start the next step. Smash and mince 5 cloves of garlic. Measure out all the dry spices into a bowl. Chop the sage and rosemary. Add 4 cups milk to a measuring glass. Grate 1 and 1/2 cups Parmesan cheese.
Make the sauce. In the same pan you wilted the spinach in, add the other half of your stick of butter, 4 tablespoons. Add 4 or 5 cloves of minced garlic. Let cook 1 minute over medium heat until fragrant.
Add 1/4 cup flour, 1 teaspoon kosher salt, 1/2 teaspoon black pepper, a pinch of cayenne pepper, and 1/4 teaspoon nutmeg. Stir and cook over medium heat for another 1 minute, until all the flour is absorbed.
Add 1 tablespoon freshly chopped sage and 1 tablespoon fresh chopped rosemary.
Immediately start to GRADUALLY pour in the 4 cups of milk. Go slow! Add 1/4 cup, then stir until the milk is absorbed. Add another 1/4 cup and do it again. Keep adding more milk until it has all been added and your roux has turned into a thickened sauce.
Once all the milk has been added, simmer the sauce for about 8-10 minutes over medium heat, turning it down to medium low once it starts to bubble on the edges. Keep it at a low simmer, no boiling allowed.
Prep the noodles: while your sauce simmers, soften your lasagna noodles. You can either boil a pot of water and add the noodles for 3 minutes, OR you can boil a kettle of water and pour it over the noodles in a casserole dish or bowl for 3 minutes. Whatever is easier for you. Drain the water after 3 minutes. We don't want our noodles to be soggy! They will continue to absorb liquid while baking in the oven.
Assemble your lasagna: Use the butter wrapper to grease a 9x13 inch pan. Set the sauce, spinach, butternut, parmesan, and noodles near the pan.
Layer the lasagna: Scoop 1 cup of sauce into the bottom of the pan.
Add 3 noodles. Add half of the butternut squash. Add half of the spinach. Add 1/2 cup Parmesan cheese. Add half of the remaining sauce.
Do it all again exactly the same: Add 3 noodles. Add half of the butternut squash. Add half of the spinach. Add 1/2 cup Parmesan cheese. Add half of the remaining sauce.
Top with the remaining 3 noodles.
Make the whipped cream. In a large bowl or stand mixer, add 1 cup heavy cream. Add 1/2 teaspoon kosher salt and 1/2 teaspoon black pepper. Beat with the whisk attachment (or the beaters) for 3-5 minutes until peaks form and it looks like whipped cream (it is whipped cream!)
Spread the whipped cream over the top layer of noodles, making sure the noodles are completely covered and nothing is poking out.
Top the whipped cream with 1/2 cup Parmesan cheese, or more, let your heart guide you.
Spray a sheet of foil with nonstick spray. Cover the lasagna.
Bake at 375 degrees F for 30 minutes. Remove the foil and bake for another 10-20 minutes, until the top is browned and starting to crisp. If it's been in the oven at least 40 minutes and the top isn't browning, you can broil it on the top rack for 1-3 minutes to help the cheese brown.
Let the lasagna settle for about 10-15 minutes before cutting into it.
Store covered in the fridge for 3-5 days.
Freezing** You can freeze individual portions for meal prep, or freeze the entire pan either unbaked or already baked. Frozen lasagna will last a good 3-4 months in the freezer! See note for details.
Make ahead: You can assemble the entire lasagna as instructed, wrap well in plastic wrap, and then keep the pan in the refrigerator to bake the next day.
To bake, remove the plastic wrap, top with foil, and let sit on the counter for about 20-30 minutes. Then, place the pan in a cold oven and set the temperature to 375 degrees. Bake for about 40-45 minutes or until heated through.
If you plan to wait longer than one day to bake, freezing is the best option. See notes.

Notes

*You can use frozen spinach if you like! Skip the sauteing step. Thaw out 8 or 10 ounces of frozen spinach, squeeze dry in paper towels, and layer in the lasagna as instructed. You won't need the 4 tablespoons butter or the 3/4 teaspoon salt called for in this step.

**Freezer instructions:

Whole baked lasagna

To freeze a whole baked lasagna, let the lasagna cool completely to room temperature. Wrap the entire pan very well in 2 layers of plastic wrap, then wrap once more in foil. You can let the pan thaw in the refrigerator overnight and follow the normal baking instructions in the recipe card (make sure to remove the plastic wrap first!). Or, let the frozen lasagna sit on the counter for about 30 minutes, making sure to remove all the plastic and recover with foil. Place the pan in the cold oven and set the temperature to 375. Because it is frozen, it will take at least twice as long so check after about 60 minutes of baking. If it's not hot all the way through, add another 20-30 minutes of time.

Whole unbaked lasagna

Assemble the entire lasagna per the instructions in the recipe card. Wrap the whole pan carefully in 2 layers of plastic wrap, then wrap in foil. You can let the pan thaw in the refrigerator overnight and follow the normal baking instructions in the recipe card (make sure to remove the plastic wrap first!). Or, let the frozen lasagna sit on the counter for about 30 minutes, making sure to remove all the plastic and recover with foil. Place the pan in the cold oven and set the temperature to 375. Because it is frozen, it will take at least twice as long so check after about 60 minutes of baking. If it's not hot all the way through, add another 20-30 minutes of time.

Nutrition