5 pounds fresh spinach, stems removed
1 cup unsalted butter
3 cloves garlic, finely sliced
1 pound ricotta cheese
2 tablespoons course salt (we used half the salt and it still was too much, go light on it)
1 3/4 teaspoons freshly ground black pepper
3 pounds wild mushrooms (chanterelles, oyster and shiitake), trimmed, cut into 1-inch pieces
3/4 cup Madeira wine
1/2 cup chopped fresh flat-leaf parsley
4 1/2 cups milk
1/2 cup all-purpose flour
1/2 teaspoon ground nutmeg
1 cup grated pecorino Romano cheese
1 one-pound package fresh spinach lasagna sheets
1. Wash spinach leaves well in three changes of cold water; shake dry. Melt 1 tablespoon butter in large pan over medium heat. Add half the garlic; saute until light golden, about 2 minutes. Add half the spinach leaves, cover, and cook, stirring occasionally, until wilted, 4 to 5 minutes. drain spinach in a colander. Repeat with another tablespoon butter and remaining garlic and spinach. When spinach is cool enough to handle, squeeze to rid it of liquid. Roughly chop spinach; place in medium bowl. Add ricotta, 2 teaspoons salt, and 1 teaspoon pepper.
2. Melt 2 tablespoons butter in a large skillet over medium heat. Add a third of the mushrooms; season with 1 teaspoon salt and 1/4 teaspoon pepper. Saute until mushrooms are softened and browned, about 10 minutes. De-glaze skillet by pouring 1/4 cup Madeira into hot skillet with mushrooms and using a wooden spoon to loosen bits cooked onto skillet. cook mushrooms until liquid has almost evaporated. Transfer cooked mushrooms to medium bowl. Repeat with another 2 tablespoons of butter, another third of the mushrooms, and 1/4 cup Madeira. (Reserve the final third of mushrooms and Madeira for topping.) Add two-thirds of the chopped parsley to bowl with cooked mushrooms; stir.
3. In medium saucepan over medium heat, heat 4 cups milk. Melt 8 tablespoons butter in medium saucepan over medium heat. When butter bubbles, add flour; cook, stirring constantly, 1 minute. Slowly add warmed milk; cook, whisking constantly, until mixture bubbles and becomes thick. Remove pan from heat. Stir in 2 teaspoons salt, 1/4 teaspoon pepper, the nutmeg, and 1/2 cup grated cheese.
4. Heat oven to 350 degrees. Set aside 1/2 cup sauce. Assemble lasagna: Spread 1/2 cup sauce in bottom of 9x13" baking pan. Place layer of lasagna sheets in pan, trimming to fit; spread 1 cup spinach mixture, 1 cup mushroom mixture, and 1/2 cup sauce on top of lasagna sheets. Repeat layers several times. For last layer, place a layer of lasagna sheets on top; spread 1/2 cup sauce over lasagna sheets. Sprinkle with 1/2 cup grated cheese. Bake lasagna until top is golden brown, 1 to 1 1/4 hours. Let stand 20 minutes before serving.
5. Just before serving, melt remaining 2 tablespoons butter in the skillet over medium heat. Add remaining third of the uncooked mushrooms; season with the remaining teaspoon salt and 1/4 teaspoon pepper. Cook until golden and tender, about 10 minutes. De-glaze skillet, with mushrooms in it, with he remaining 1/4 cup Madeira. Stir in the remaining third of fresh parsley.