1-1/2 tablespoons olive oil
1 onion
1 carrot, finely chopped
1 celery stalk, finely chopped
3/4 pound mushrooms, chopped (about 4 cups)
2 cloves garlic, finely chopped
1/2 cup dry white wine
1 28-ounce can plum tomatoes, chopped with juices 2 sun-dried tomatoes (not packed in oil) finely chopped
1 teaspoon dried thyme leaves
salt and freshly ground pepper
1/3 cups all purpose while flour
3 cups milk or cream
1/4 teaspoon freshly ground nutmeg
1 pound fresh lasagna noodles
8 cups spinach leaves, washed and dried
1 cup freshly grated Parmesan cheese
Heat 1/2 tablespoon of the oil in a Dutch oven over medium heat. Add onions, celery, carrots and cook stirring until the onions have softened. Add mushrooms and garlic and continue to cook until the mushrooms release their liquid, 2 or 3 minutes. Add wine and cook until most of the liquid has evaporated. Stir in chopped tomatoes and their liquid, sun-dried tomatoes and thyme. Bring to a simmer. Reduce heat to low and simmer until thick. Season with salt and pepper. Heat remaining oil in heavy pan over low heat. Add flour and cook whisking constantly until the flour starts to turn a light nutty brown. Remove from heat and whisk in milk. Season with nutmeg and salt to taste. Remove from heat and set aside. Preheat oven to 375. Cook lasagna in boiling water.
To assemble, spread 1/2 cup of the mushroom sauce in the bottom of a pan. Arrange a layer of cooked noodles over and spread with another 1/2 cup of the mushroom sauce. Arrange a single layer of the spinach leaves over the sauce and drizzle them with 1/3 cup of the bechamel sauce. Sprinkle 2 tablespoons of the Parmesan cheese over the spinach and top with another layer of the noodles. Repeat this five more times. Bake 40 minutes.