Optional garnish: chopped fresh parsley or other herbs
Instructions
Preheat oven to 400°F. Grease a deep 13 x 9-inch baking dish; set aside.
PREPARE THE BUTTERNUT SQUASH:
Slice squash vertically down the center, and scoop out the seeds. Rub olive oil all over the squash, and place the halves cut-side down on a baking sheet lined with parchment paper. Roast in the oven for about 50-60 minutes, or until very tender.
Allow squash to cool, peel the skin off, and transfer the flesh to a food processor or blender.
Add the milk, thyme, sage, salt, and pepper. Blend until smooth; set aside.
PREPARE THE MUSHROOMS:
Melt the butter in a large skillet over medium-high heat. Add the onions and saute until soft, about 8 minutes. Increase the heat to high, add the mushrooms, thyme, and sage, and cook until tender, about 3 more minutes. Remove from the heat. Season with salt and pepper to taste. Set aside.
PREPARE THE RICOTTA SPINACH LAYER:
Squeeze all of the liquid out of the spinach. I like to use a dish towel for this, and just keep squeezing until you wring out as much water as possible. Place spinach in a large bowl.
Add ricotta, mozzarella, Parmesan, egg, salt, garlic powder, and nutmeg to the bowl with the spinach. Stir really well with a fork to combine.
ASSEMBLE THE LASAGNA:
Spread about ¾ cup of the butternut squash mixture on the bottom of the prepared baking dish. Top with a layer of no-boil lasagna noodles (using as many as you need to cover a single layer in the dish), ½ of the ricotta mixture, and ½ of the mushroom mixture.
Add a heaping 1 cup of the butternut squash mixture on top, another layer of noodles, the remaining ricotta mixture, and the remaining mushrooms.
Spread any remaining butternut squash on top. Finish with 1 ½ cups of shredded mozzarella cheese and ¼ cup of grated Parmesan cheese.
Cover the dish with foil.
Bake for 25 minutes. Remove the cover and bake for about 15 more minutes, until the filing is hot and bubbly and the cheese on top is nicely browned.
Let stand for at least 15 minutes before slicing and serving. Garnish with additional chopped fresh herbs, if desired.