Preheat your oven to 375°F and cook lasagne noodles according to the directions on the box. Strain your pasta and set it aside to cool (see first note below).
Dice your onion, chop your mushrooms, and mince your garlic. Add them to a large saucepan with the spinach, olive oil, salt, and pepper over high heat, stirring occasionally, until all of the liquid evaporates (about 15 minutes).
Add about 2 tablespoons of sauce to a 9x13-inch casserole dish and spread it out evenly to form a thin bottom layer of sauce.
Place 3 noodles on top in a single layer. Then, spread about 1/2 of your ricotta across the top of the noodles. Next, add roughly 1/2 of your cooked veggies and top with a thin layer of Italian blend shredded cheese.
Repeat step 4, using up the ricotta and cooked vegetables.
After your second layer of shredded cheese, add a third layer of lasagna noodles, a third layer of sauce, and a final layer of shredded cheese. Top it off with the Parmesan cheese
Bake for 25-30 minutes until the cheesy top starts to brown. Option to garnish with fresh basil. Enjoy!