Spinach, Mushroom and Goat Cheese Lasagna

2 tablespoons butter

1-pound sliced baby bella mushrooms

20 ounces baby spinach

Goat Cheese Bechamel: 

1/2 cup flour

1/2 cup butter

4 cups milk

8.5 ounces soft goat cheese

32 ounces shredded mozzarella

14 oven-ready lasagna sheets

Salt, to taste

Heat oven to 350F. Line a 9×13 baking pan or dish with foil. 

In a large skillet over medium heat, melt 2 tablespoons butter. Add mushrooms and cook until wilted, about 5 minutes. Transfer to a mixing bowl. Add half the spinach to the pan and cover until spinach is wilted, about 3 minutes. Add to mushrooms. Repeat with remaining spinach. Season mixture with salt to taste. Let cool while making bechamel. 

In a saucepan or Dutch oven over medium heat, melt 1/2 cup butter. Whisk in flour, then gradually whisk in milk. Continue whisking until thickened, then whisk in goat cheese a little at a time until melted. Season with salt to taste. 

To build the lasagna, spread 1/4 bechamel on the bottom of the prepared pan, then cover completely with a layer of noodles, breaking them to fit if necessary. Cover with another 1/4 bechamel, then 1/3 mushroom mixture, then 1/3 mozzarella. Cover with noodles, then bechamel, then mushroom mixture, then mozzarella. Repeat until out of ingredients. Finish with mozzarella. Cover with foil and bake until noodles are soft, and cheese is melted, about 35 minutes. Remove foil and bake until browned, about 10 minutes more. Let stand 15 minutes before cutting.