Preheat oven to 425°F. Arrange cherry tomatoes, bell peppers, mushrooms, zucchini, onion, and whole garlic head on a baking sheet.
Drizzle vegetables with olive oil, sprinkle Italian seasoning, salt, and pepper, then toss to coat evenly.
Roast vegetables for 25–30 minutes until tender and lightly charred.
Allow roasted vegetables to cool slightly. Squeeze garlic cloves from skin into a blender.
Add roasted vegetables, vegan cream cheese, tomato paste, and fresh basil to the blender, and blend until smooth and creamy.
Season sauce with salt and pepper as needed.
Cook pasta according to package directions until al dente. Reserve 1–2 tablespoons of pasta water before draining.
Heat the blended sauce in a pan over medium heat.
Add cooked pasta to the sauce and toss gently to combine.
Adjust sauce consistency with reserved pasta water if needed, warming for 2–3 minutes while stirring.
Serve pasta hot, topped with fresh basil leaves and optional chili flakes.