Bring a large pot of salted water to a boil and cook the pasta until just al dente, then drain and set aside.
While the pasta cooks, heat olive oil in a sauté pan and add diced onion, cooking until translucent and fragrant, about 3 minutes.
Add chopped zucchini and bell pepper to the pan, sautéing until vegetables are tender and slightly caramelized, approximately 7 minutes. Remove from heat.
Drain soaked cashews and transfer them to a blender, adding nutritional yeast, minced garlic, lemon juice, plant-based milk, salt, and pepper. Blend until smooth and creamy, stopping to scrape down sides as needed.
Combine the cooked pasta with the sautéed vegetables and cashew sauce in a large mixing bowl, stirring well to coat everything evenly.
Transfer the pasta mixture into a greased baking dish, spreading it out evenly.
Sprinkle vegan cheese or breadcrumbs evenly over the top for a crispy, golden crust.
Bake in a preheated oven at 180°C (350°F) for 25-30 minutes, until bubbling and the top is golden brown.
Remove from the oven and let it rest for 10 minutes — this helps the layers set and makes serving easier.
Garnish with fresh herbs if desired, then slice and serve warm, enjoying the cheesy, hearty textures.