Preheat your oven to 375°F (190°C). Spread the sliced zucchini, eggplant, and chopped bell pepper on a baking sheet, drizzle with a tablespoon of olive oil, sprinkle with salt and pepper, and roast for about 20 minutes until tender and slightly caramelized.
Meanwhile, cook the ziti pasta in a large pot of salted boiling water until just shy of al dente, about 8 minutes. Drain and set aside.
In a saucepan, heat the olive oil over medium heat. Add the diced onion and minced garlic, cooking until fragrant and translucent, about 3-4 minutes. Stir in crushed tomatoes and herbs, simmering for 10 minutes to develop the flavors.
In a large mixing bowl, combine the cooked pasta with the tomato sauce, roasted vegetables, and chopped bell pepper. Mix gently to evenly coat everything in the sauce.
Layer half of the pasta mixture into a greased baking dish. Dot with dollops of plant-based ricotta and sprinkle with half of the shredded vegan mozzarella and nutritional yeast.
Add the remaining pasta mixture on top, then evenly distribute the remaining ricotta, mozzarella, and nutritional yeast over the surface.
Bake uncovered in the preheated oven for 20-25 minutes, or until bubbling around the edges and the cheese topping is golden and slightly crispy.
Remove from the oven and let it rest for 5 minutes; this helps the cheese set slightly for easier slicing.
Slice and serve your vegan baked ziti hot, garnished with fresh herbs if desired, and enjoy the hearty, cheesy goodness.
