Butternut Squash Spinach Lasagna

Spinach Pasta

Squash filling:

2 tablespoons butter

2/3 cup water

1/4 teaspoon salt

6 cups peeled, cubed butternut squash

Mushroom & onion filling:

6 cups white or portabella mushrooms, sliced or diced

2 tablespoons olive oil, divided

1/8 teaspoon salt
1/2 teaspoon dried thyme or 1 teaspoon fresh thyme, minced

2 medium-large sweet onions, peeled and sliced

White sauce:

1/4 cup (4 tablespoons) butter

1/3 cup unbleached all-purpose flour

1/2 teaspoon salt

3 cups whole milk

1 cup grated Parmesan cheese, divided

Cheese filling:

2 cups ricotta cheese, whole milk or part skim

1 large egg

1/4 teaspoon salt

1 cup grated mozzarella

To prepare the squash: Place water, butter, and salt in a large frying pan. Add the squash; it should be in a single layer. Cover the pan, and simmer for 5 minutes, or until the squash is starting to soften. Remove the cover, increase the heat, and cook, tossing occasionally, until the water evaporates and the squash browns, about 15 minutes. Remove it from the pan, and set it aside.  (Alternatively, roast diced squash, drizzled with oil or melted butter and seasoned with salt and pepper, in a 400° F oven for 30 minutes.)

To prepare the mushrooms and onions: Using the pan that the squash was cooked in, if desired, sauté the mushrooms in 1 tablespoon of the oil, with the salt, until they've released their liquid, and are browned.  Add the thyme a few minutes before mushrooms are done.  Remove them from the pan, and set them aside. Add the remaining 1 tablespoon oil to the pan, and sauté the onions until they're golden brown, 20 to 25 minutes.

To prepare the cheese filling: Melt the butter in a large saucepan. Stir in the flour and salt.  Whisk in the milk, stirring constantly, until all the milk is added and no lumps remain. Cook over medium heat, stirring frequently, until the sauce thickens.  Remove the sauce from the heat, and stir in 1/2 cup of the Parmesan cheese.

To assemble the lasagna: Pour about 1 cup of the white sauce into the bottom of a lightly greased 9" x 13" pan, or similarly sized casserole dish. Place three noodles on top.  Arrange the squash on top. 

Top the squash with three more noodles.  Spread the ricotta cheese over the noodles. 

Add three more noodles, and another cup of the sauce.  Sprinkle with grated mozzarella.  Spread the mushroom/onion mixture evenly over the sauce. 

Add the last three noodles, and top with the remaining sauce. Sprinkle with the remaining grated Parmesan.

Cover the lasagna, and bake it in a preheated 375°F oven for 45 minutes. Remove the cover, and bake for an additional 40 to 45 minutes, or until the top of the lasagna is nicely browned.  Check frequently for the last 20 minutes or so to make sure it isn't browning too much.

Remove the lasagna from the oven, and let it rest for 15 minutes before serving.

Serves 8-12.

From King Arthur Flour, with some changes