Preheat oven to 400 F and line a large baking sheet with parchment paper

Place sliced eggplant on the prepared baking sheet and sprinkle with salt. Roast for 30 minutes. Set aside

While the eggplant is roasting, in a large bowl combine spinach, ricotta cheese, eggs, oregano, 1/3 cup Parmesan cheese, ½ teaspoon salt, garlic and nutmeg. Set aside

Generously grease 10 x 10-inch baking dish with olive oil and line the bottom with roasted eggplant, following with ½ spinach mixture, ½ basil leaves, ½ tomatoes, ½ mushrooms, then continue with the same layers. Firmly press down. Set aside

Reduce oven temperature to 375 F

In a small pot whisk together, milk, 1/3 cup parmesan cheese, tapioca flour, black pepper and balance of salt (1/2 tsp.) Cook over medium heat while stirring, until the sauce starts to thicken, about 3 – 5 minutes

Pour sauce over lasagna and sprinkle with remaining 1/3 cup of Parmesan cheese Bake for 35 - 40 minutes until the cheese is bubbling.