Preheat the oven to 400°F (200°C). Spread cherry tomatoes, bell peppers, mushrooms, zucchini, and onion on a baking tray and place the trimmed garlic head cut-side up.
Drizzle vegetables with olive oil, sprinkle with Italian seasoning, salt, and pepper, then toss to coat evenly.
Roast the vegetables for 25–30 minutes until soft and slightly caramelized.
While vegetables roast, cook the pasta according to package instructions until al dente; reserve 1–2 tablespoons of pasta water before draining.
Squeeze softened garlic cloves from skins into a blender. Add roasted vegetables, vegan cream cheese, tomato paste, and fresh basil.
Blend until smooth and creamy, adding reserved pasta water gradually to achieve desired sauce consistency.
Return drained pasta to the pot, pour the blended sauce over it, and toss until fully coated and heated through.
Serve garnished with fresh basil leaves and optional chili flakes.