Preheat oven to 375 degrees. Coat an 8 x 8-inch baking pan with olive oil cooking spray.
In a large skillet over medium heat, cook the mushrooms and onion for 10-15 minutes or until tender.
Add the garlic and cook for 60 seconds, stirring frequently, then season with sea salt and freshly cracked pepper.
In a large bowl, add ricotta, egg, ½ cup of mozzarella cheese, Parmesan cheese, oregano, fresh chopped basil, sea salt, and freshly cracked pepper to taste. Combine until mixed thoroughly.
Layer an 8 x 8-inch baking pan with just enough sauce to cover the bottom of the pan.
Lay two lasagna noodles in the pan.
Spread some of the ricotta mixture on the noodles, then spoon some of the mushroom mixture on top.
Finish by layering some spinach leaves on top; repeat layering.
Finish with a layer of noodles and the sauce.
Sprinkle with the remaining mozzarella cheese, then top with a dash of dried basil.
Bake covered for 30 minutes.
Uncover and bake for 15 minutes.
Let it rest for 10-15 minutes before slicing and serving. Enjoy.