Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.
If frozen spinach is clumped or watery, thaw and squeeze out excess liquid; chop if large leaves remain.
In a large mixing bowl, combine grated carrots, grated zucchini, spinach, chopped bell pepper, diced tomatoes, tomato sauce, oregano, dried basil, onion powder, garlic powder, mushrooms, and salt to taste; stir until evenly mixed.
Spread a layer of lasagna noodles in the bottom of the prepared dish.
Sprinkle 1/2 cup of the grated Parmesan over the noodles, then spread half of the vegetable mixture on top.
Add another layer of noodles, sprinkle another 1/2 cup Parmesan, and spread the remaining vegetable mixture over them.
Top with a final layer of noodles, the remaining Parmesan, and then evenly scatter the grated mozzarella over the top.
Bake in the preheated oven for 40 minutes, until heated through and cheese is melted and bubbly.
Remove from oven and let rest a few minutes, then garnish with chopped fresh basil if desired and serve.
