Butternut Squash Lasagna with Caramelized Onions and Smoked Mozzarella

Paula Forbes
Paula Forbes
October 18, 2023
This is a decadent vegetarian entree that will be welcome on any holiday table (even alongside meat dishes). The Anova Precision Oven makes an otherwise complex dish easy. The steam feature allows you to cook butternut squash to tender perfection. Then, once the lasagna is constructed, it becomes a golden brown, bubbling showstopper in record time thanks to steam-roasting. Notes: you can prep and construct the lasagna the day before if you like. Leave the final topping of cheese off until you’d like to bake the lasagna. Refrigerate it, covered, overnight, and add 5 minutes to the final cooking step.
Prep Time
Cook Time
Butternut Squash Lasagna with Caramelized Onions and Smoked Mozzarella
¼ cup plus 2 Tbsp
extra-virgin olive oil, divided
Kosher salt and freshly ground black pepper
4 large
yellow onions, thinly sliced
1 (3 1/2 to 4 lb)
butternut squash, peeled, sliced in half lengthwise, seeds removed
4 cups
whole milk
2 sprigs
fresh thyme
2 sprigs
fresh sage
1 sprig
fresh rosemary
bay leaf
¼ cup
all-purpose flour
4 Tbsp
unsalted butter
1 lb
dry lasagna noodles
1 cup
ground pecorino
8 oz
smoked mozzarella, grated

1. Heat the Oven

Sous Vide Mode: Off
Steam: 100%
Temp: 325°F
Heat: Rear

2. Caramelize the Onions

Heat a large saute pan over medium-low heat and add ¼ cup olive oil. Add the sliced onions and ½ teaspoon salt. Cook the onions, stirring frequently (and more frequently towards the end), until deep golden brown, 45 minutes to 1 hour.
Caramelize the Onions

3. Season the Squash

While the onions are caramelizing, brush each half of the squash with 1 ½ teaspoons oil, then season with a large pinch of salt and several grinds of black pepper. Place on a sheet pan, cut side down.
Season the Squash

4. Roast the Squash

Place the squash in the oven. Cook for 25 minutes, until the squash is just starting to turn tender. Remove the squash from the oven and set aside to cool.
Sous Vide Mode: Off
Steam: 100%
Temp: 325°F
Heat: Rear
00:25 Timer

5. Adjust the Oven for the Lasagna

Sous Vide Mode: Off
Steam: 50%
Temp: 350°F
Heat: Rear

6. Prepare the Squash

Once the squash has cooled enough to handle, slice it crosswise into ¼-inch-thick pieces.
Prepare the Squash

7. Infuse the Milk

Bring the milk to a simmer in a medium saucepan. Add the herbs and bay leaf and remove from heat to steep for 10 minutes.

8. Prepare the Roux

In a large saucepan, melt the butter over medium-low heat. Whisk in the flour, then continue whisking for another minute.
Prepare the Roux

9. Make the Sauce

Remove the herbs from the milk. Pour 1 ladleful of warm milk into the roux, whisking until smooth. Repeat until you have used all of the milk. Continue whisking until the sauce thickens, 4 to 6 minutes. You should have achieved a silky, luxurious sauce. Season to taste with salt and pepper.
Make the Sauce

10. Cook the Pasta

Bring a large pot of salted water to a boil. Add the lasagna noodles and cook for 2 minutes less than what’s called for on the package instructions. When they are done, drain them well, rinse with cold water to stop the cooking process, and toss with 1 tablespoon olive oil to ensure they don’t stick to each other.

11. Build the Lasagna

In a 9- by 13-inch lasagna pan, spread a generous spoonful (about ½ cup) of the bechamel over the bottom of the pan and cover with lasagna noodles. Cover the noodles with ¾ cup bechamel, then dust with ¼ cup pecorino. Tile one third of the squash slices over the sauce, then sprinkle one third of the caramelized onions evenly over the top. Finally, dot the onions with a quarter of the mozzarella. Repeat this layering—noodles, bechamel, pecorino, squash, onions, mozzarella—twice more. For the final layer, cover the noodles with the last of the bechamel, pecorino, and mozzarella.
Build the Lasagna

12. Bake the Lasagna

Transfer to the oven and bake the lasagna until bubbly and browned on top, about 20 minutes. Let cool for 10 minutes, and serve.
Bake the Lasagna
Sous Vide Mode: Off
Steam: 50%
Temp: 350°F
Heat: Rear
00:20 Timer
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