Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the penne and return to a boil. Cook the pasta uncovered, stirring occasionally until the pasta has cooked through but is still firm to the bite, about 8 minutes. Drain well in a colander set in the sink. Rinse with cold water to stop the cooking process. Transfer to a large roasting pan.
Whisk together 450g pasta sauce and the ricotta cheese in a large bowl. Add to the pasta and stir.
Place the spinach in the bowl of a food processor and blend until finely chopped; remove and set aside. Then place the carrots in the food processor and process until finely chopped.
Heat the olive oil in a large frypan over medium-high heat. Cook the chopped carrots in the hot oil until they begin to soften, about 2 minutes. Stir in the zucchini, portobella mushrooms, button mushrooms and garlic; cook and stir until the zucchini is soft, about 4 minutes. Remove from heat and stir in the chopped spinach, tomatoes and 2 tablespoons Italian herb mix; drain. Add to the penne and mix. Sprinkle about 1/2 of the Italian cheese blend over the pasta and stir through. Pour in the remaining pasta sauce; stir until the pasta and vegetables are evenly coated. Season with 2 tablespoons Italian herb mix, salt and pepper; mix. Cover the pan with aluminium foil.
Bake in the preheated oven until completely heated through, 1 to 1 1/2 hours. Remove the foil and sprinkle the remaining cheese over the dish. Return dish to oven and bake until the cheese melts and begins to brown, about 10 minutes more.