Preheat oven to 420°F (215°C).
Toss tomatoes, onion, and garlic head with olive oil and salt on a large baking sheet.
Roast for 35 minutes until vegetables are softened and golden brown.
Transfer roasted vegetables to a blender or large pot, squeezing garlic cloves from their skins.
Add vegetable broth, butter beans, tomato paste, maple syrup, and fresh basil leaves.
Blend until completely smooth and creamy.
Transfer to a pot and warm over medium heat for 5-10 minutes.
Stir in oat milk or vegan cream for extra creaminess if desired.
Season with salt and pepper to taste.
Serve hot, garnished with fresh basil leaves.