In a large pan on medium heat add the butter, garlic powder, & Italian seasoning. Let butter melt.
Once the butter is melted add the mushrooms. Mix and coat mushrooms in butter mixture and cover. Cook for 8-10 minutes stirring occassionally.
Add spinach and cover or 2 minutes. Uncover and stir until wilted. Remove mushrooms and spinch from heat.
In a large mixing bowl add the spinach and mushrooms, ricotta, pesto, parmesan cheese and 1 cup of shredded mozzarella. Mix until well combined.
In a 9" x 13" baking dish pour 1.5 cups of tomato sauce on the bottom of the dish and evenly spread it out.
Add a layer of lasagna noodles. Add a layer of the ricotta cheese mixture, spread making an even layer. Add a layer of sauce. Add another layer of lasagna noodles. Add another layer of ricotta cheese mixture. Add another layer of noodles. Pour 1 cup of tomato sauce on top. Sprinkle with the remaining shredded mozzarella on top.
Place in the oven at 350ºF for 45 minutes.
Enjoy with some crusty Italian bread & garden salad!