Boil the cashews for 15 minutes. Once boiled, transfer to a blender and blend with the ½ cup of water until smooth and creamy. Set aside.
Heat the oil in a large pot over medium heat.
Once heated, add half of the basil leaves, the onion, and the garlic and saute until the onion is just starting to turn translucent.
Add the tomato paste and continue cooking, stirring frequently for 7-8 minutes.
Add the cans of tomatoes and vegetable broth. Increase the heat to high and bring to a simmer. Let it simmer for 40 minutes uncovered, stirring occasionally. You may need to adjust the heat during this time to keep the soup simmering.
After 40 minutes, add the cashew cream and remaining basil and mix in.
Transfer the soup to a blender in batches and blend until smooth and creamy. Be sure to only fill the blender about ⅔ of the way for each batch. Pour the soup from the blender into a bowl.