Preheat oven to 190 degrees C. Grease a 9x13-inch casserole dish.
Bring a large pot of lightly salted water to a boil. Add lasagna noodles and cook for 8 to 10 minutes or until al dente; drain.
Heat oil in a large cast iron skillet over medium heat. When oil is hot add broccoli, carrots, onions, bell peppers, zucchini and garlic. Saute for 7 minutes; set aside.
Place flour in a medium saucepan and gradually whisk in milk until well blended. Bring to a boil over medium heat. Cook 5 minutes, or until thick, stirring constantly. Stir in 1/2 cup Parmesan cheese, salt and pepper; cook for 1 minute, stirring constantly.
Layer noodles, ricotta mixture, vegetable, and 2 cups mozzarella cheese, ending with noodles. Top with reserved spinach mixture, 1/2 cup mozzarella cheese and 1/4 cup parmesan cheese.
Bake in preheated oven for 35 minutes, or until lightly browned on top. Cool for approximately 10 minutes before serving.