• Preheat the oven to 375°F.
• Cook the lasagna noodles according to the package instructions and set aside.
• In a skillet, sauté the sliced mushrooms, baby spinach, and minced garlic in olive oil until the vegetables are tender and the liquid has evaporated.
• In a mixing bowl, whisk together the béchamel sauce with the cooked vegetables and season with salt and pepper to taste.
• In a lasagna dish, layer the cooked lasagna noodles, béchamel sauce and vegetable mixture, and shredded mozzarella cheese, repeating until all ingredients are used up.
• Sprinkle the grated parmesan cheese on top of the lasagna.
• Bake in the oven for 45 minutes, or until the cheese is melted and bubbly.
• Remove from the oven and allow the lasagna to cool for a few minutes before serving.

Béchamel Sauce:

• In a large pot, melt the butter over medium heat.
• Add the flour and whisk until smooth.
• Gradually add the milk, whisking constantly to prevent lumps from forming.
• Cook the sauce, stirring constantly, until it thickens and coats the back of a spoon.
• Remove from heat and season with salt and black pepper.