Preheat your oven to 375 degrees F. Boil the lasagna noodles according to package directions, drain, and set aside.
Heat olive oil in a large skillet over medium heat. Add the diced zucchini, bell peppers, and minced garlic. Saute for 5-7 minutes until tender. Stir in the fresh spinach and cook for 2 minutes until wilted. Remove from heat.
In a medium bowl, combine the ricotta cheese with the finely chopped fresh parsley.
Spread 1 cup of marinara tomato sauce on the bottom of a 9x13 inch baking dish. Place 3 to 4 lasagna noodles over the sauce. Spread a third of the ricotta mixture over the noodles, top with a third of the vegetable mixture, and sprinkle with 1 cup of mozzarella cheese.
Repeat the layers two more times, finishing with a final layer of noodles, the remaining marinara sauce, and the last of the mozzarella cheese on top.
Cover the baking dish tightly with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is melted and bubbling.
Let the dish rest for 15 minutes before slicing and serving.