Heat the olive oil and sauté the onion and the garlic for about 2-3 minutes. Then add the tomatoes and the basil. Cook for a minute. Transfer to a blender, add the cashews and the nutritional yeast, and blend until smooth.
Season the soup with salt, pepper, and red pepper flakes and cook for about 3 minutes. Top it with cashew or soy cream, more chopped basil, and red pepper flakes. Serve with fresh bread or vegan cheese sandwiches.