Butternut Squash Lasagna with Walnuts and Sage

Lasagna is a labor of love. If I’m going to put in the effort, I want a spectacular result, and my standards are just as high for a vegetarian lasagna.

This butternut squash lasagna became that recipe after several test batches. Rather than roasting or puréeing the squash first, I slice it thinly and add it to the lasagna raw. It becomes tender as the lasagna bakes without turning to mush.

No-boil noodles and a simple four-layer structure keep the assembly manageable, but this is still a relaxed Sunday-afternoon project, not a rushed weeknight dinner. The payoff is a bubbling, golden-topped lasagna with sweet squash, savory shallots, woodsy sage, and earthy walnuts in every layer.

Instead of the usual ricotta-and-egg filling, I use garlic béchamel, a creamy white sauce made with olive oil. It binds the layers without overwhelming the delicate squash. Bring it to the table for a cozy family supper, dinner party, or meatless holiday centerpiece.

Butternut Squash Lasagna Ingredients 

This recipe uses two main components: a savory squash filling and an olive-oil béchamel. Here is what you’ll need and why each ingredient matters. 

For the Squash Filling

• Butternut squash: You’ll start with a 2 1/2-pound squash and use about 2 pounds, or 8 cups, once it is peeled, seeded, and sliced. Cutting the squash into even 1/4-inch slices is important so it cooks at the same rate as the noodles.
• Extra virgin olive oil: One tablespoon is enough to sauté the shallots, walnuts, and sage. A flavorful extra virgin olive oil adds richness without making the filling greasy.
• Shallots: Sautéed shallots provide a mellow, savory-sweet foundation for the filling. You can substitute an equal amount of thinly sliced red onion.
• Walnuts: Finely chopped walnuts add earthy flavor and a welcome bit of texture between the tender squash and noodles.
• Fresh sage: Sage’s woodsy, peppery flavor is a natural match for sweet winter squash. Thinly slice the leaves for the filling. For an optional crispy garnish, fry a few whole sage leaves in a spoonful of olive oil.
• Kosher salt and black pepper: Seasoning the filling—and each layer of squash—keeps the finished lasagna from tasting flat.
• No-boil lasagna noodles: These noodles cook directly in the sauce, which eliminates a separate boiling step. If you use regular lasagna noodles, prepare them according to the package instructions and blot them dry before assembling the lasagna.
• Mozzarella and Parmigiano-Reggiano: Mild mozzarella melts smoothly and helps hold the layers together. Parmigiano-Reggiano adds a salty, nutty finish.

For the Garlic Béchamel

• Extra virgin olive oil: Olive oil replaces the butter traditionally used to begin béchamel. Choose a mild, smooth oil, such as our Arbequina California olive oil, so it doesn’t overpower the sauce.
• Garlic: Four minced cloves gently infuse the béchamel with savory flavor.
• All-purpose flour: Flour thickens the sauce and gives it enough body to coat the noodles while remaining pourable.
• Milk: The recipe uses 2% milk for a creamy sauce that isn’t overly heavy. Whole milk will produce a richer béchamel.
• Kosher salt and black pepper: Béchamel needs enough seasoning to balance its mild dairy base. Taste the finished sauce and add another pinch of salt if necessary.
• Nutmeg: A small amount of freshly grated nutmeg adds subtle warmth without making the sauce taste sweet.

How to Make Butternut Squash Lasagna

The key to this recipe is preparing each component before you begin layering. If you make the béchamel in advance, reheat it gently and whisk until smooth before assembling the lasagna. 

• Prepare the squash. Trim the stem and bottom from a 2 1/2-pound butternut squash. Peel it, halve it lengthwise, and scoop out the seeds. Set each half cut-side down and slice it crosswise into 1/4-inch-thick pieces. You should have about 8 cups, or 2 pounds, of sliced squash. Reserve any extra for another use.
• Sauté the aromatics. Heat 1 tablespoon extra virgin olive oil in a large skillet over medium-high heat. Add 2 cups thinly sliced shallots and cook, stirring, until golden brown, about 3 minutes. Add 2/3 cup finely chopped walnuts and 1/2 cup thinly sliced sage. Cook until the sage wilts, about 2 minutes. Season with 1/2 teaspoon kosher salt and a generous amount of black pepper.
• Start the garlic béchamel. Heat 1/4 cup extra virgin olive oil in a saucepan over medium-low heat. Add 4 minced garlic cloves and cook for 1 minute. Whisk in 4 tablespoons all-purpose flour and cook, stirring, for 3 minutes.
• Add the milk gradually. Increase the heat to medium. Add 4 cups of 2% milk a few tablespoons at a time, whisking constantly and waiting until the sauce is smooth before adding more. Once all the milk is incorporated, continue cooking and whisking often until the sauce reaches a simmer, about 20 to 25 minutes.
• Finish the béchamel. Reduce the heat to low and whisk until the sauce is thick enough to coat the back of a spoon. Add 1/2 teaspoon kosher salt, several grinds of black pepper, and 1/2 teaspoon finely grated nutmeg. Remove the pan from the heat. The béchamel should be thick but still easy to pour. Taste and add another pinch of salt if needed.
• Combine the cheeses. In a small bowl, toss together 2 cups coarsely grated part-skim mozzarella and 1 cup finely grated Parmigiano-Reggiano.
• Prepare the baking dish. Preheat the oven to 375°F. Brush a 9-by-13-inch glass baking dish with olive oil, then spread about 3/4 cup of the béchamel evenly over the bottom.
• Build the first layer. Arrange 3 no-boil lasagna noodles over the sauce. Spread another 3/4 cup of béchamel over the noodles. Add one-quarter of the squash slices, overlapping them slightly, and season the squash with salt and pepper. Top with one-quarter of the shallot-walnut mixture and one-quarter of the cheese mixture.
• Repeat the layers. Make three more layers in the same order: noodles, béchamel, squash, salt and pepper, shallot-walnut mixture, and cheese. Finish with the cheese mixture and add a few fresh sage leaves on top, if you like.
• Bake until tender. Cover the dish with foil and bake for 1 hour. Remove the foil and insert a sharp paring knife through the center. It should slide easily through both the squash and noodles. If the squash is still firm, cover the dish again and bake for up to 15 minutes more.
• Broil the top. Remove the foil and switch the oven to broil. Broil until the cheese is bubbling and golden brown, watching it carefully so it does not burn.
• Rest and serve. Let the lasagna cool for 10 minutes before slicing. Garnish with fried sage leaves, if you like.

Tips for the Best Butternut Squash Lasagna 

• Slice the squash evenly. Aim for 1/4-inch-thick slices. Thicker pieces may remain firm after the noodles are tender, while very thin pieces can become too soft.
• Add the milk slowly. Incorporating a few tablespoons at a time makes it easier to whisk the flour mixture smooth and prevent lumps.
• Watch the béchamel’s consistency. It should coat the back of a spoon but remain pourable. The noodles need that moisture to cook properly.
• Divide before you layer. Mentally divide the squash, shallot-walnut mixture, and cheese into quarters before assembly. This prevents you from running short before the final layer.
• Use a knife to test the center. The browned top cannot tell you whether the squash underneath is done. A sharp paring knife should slide through the squash and noodles easily.
• Stay near the broiler. Cheese can go from golden to burned quickly, particularly around the edges of the baking dish.

Make It Your Own

Lasagna depends on the right balance of sauce, noodles, filling, and moisture, so I don’t recommend replacing the squash with another vegetable or swapping the béchamel for a different sauce. You can still make a few smaller adjustments: 

• Swap the nuts: Finely chopped hazelnuts would be lovely instead of walnuts. Or skip the nuts altogether, if you like a uniformly soft texture. For a nut-free option, use roasted pepitas.
• Swap the herbs: Use fresh thyme instead of sage.
• Change the garnish. I liked the look of the walnuts on top of the finished lasagna, but if you want a cleaner-looking top, split the walnut-shallot mixture among the inner layers instead. 
• Use your favorite cheeses: I like the combination of a mild cheese, like mozzarella, with a saltier and more flavorful cheese like Parmesan. But choose your own favorite combo. Unaged fontina and Pecorino-Romano would also be nice. Or, for even more cheesy flavor, try Gruyere and Parmesan. 

What to Serve with Butternut Squash Lasagna 

Butternut squash lasagna is rich and creamy, so I like to serve it with something fresh and crisp. This colorful orange salad with endive and radicchio balances the lasagna with sweet citrus, pleasantly bitter greens, and a tangy vinaigrette.

For something milder, try a delicate butter lettuce salad with tarragon vinaigrette. You can also continue the Italian-American theme with a classic Caesar salad.

If you’re serving company, add homemade garlic bread or rosemary and roasted garlic focaccia for soaking up any béchamel left on the plate. Finish the meal with an Italian pear cake with citrus and honey.

Make Ahead and Store 

This lasagna is at its best when it is freshly baked. I don’t recommend baking the entire dish in advance because the squash becomes softer when reheated. You can still prepare several components ahead to make assembly easier:

• Prepare the squash: Trim, peel, seed, and slice the squash. Transfer it to a zip-top bag and refrigerate overnight.
• Cook the filling: Sauté the shallots, walnuts, and sage, then refrigerate the mixture overnight.
• Make the béchamel: Let the sauce cool completely, then press plastic wrap directly against its surface to prevent a skin from forming. Refrigerate it, then reheat over low heat and whisk until smooth before assembling the lasagna.
• Assemble now and bake later: You can assemble the unbaked lasagna, cover it, and refrigerate it. Let it come to room temperature before baking.

Store leftover butternut squash lasagna in the refrigerator for up to four days. To reheat an individual serving, cover it lightly with foil and warm it in a 350°F oven for about 15 minutes.