Preheat your oven to 400°F (200°C). Toss the cubed squash with 1 tbsp of olive oil, salt, and pepper. Roast for 25 minutes until fork-tender.
While the squash roasts, heat the remaining 1 tbsp of olive oil in a skillet over medium heat. Sauté the diced onion for 5 minutes until translucent, then add the minced garlic and tomato paste, cooking for 1 more minute.
Transfer the roasted squash, sautéed onion and garlic mixture, vegetable broth, soaked cashews, and nutritional yeast to a high-speed blender. Blend on high until completely smooth.
Bring a large pot of salted water to a boil. Cook the fusilli according to the package instructions until al dente, then drain (reserving 1/4 cup of pasta water).
Toss the cooked fusilli with the blended mixture, adding reserved pasta water as needed to reach your desired consistency. Serve warm, topped with vegan grated cheese.