How to Make It
Preheat the oven to 400°. Toss together 2 pounds of green tomatoes, 2 tablespoons of the olive oil, salt and pepper. Spread the tomatoes in an even layer on a baking sheet and roast for 30 minutes.
In an eight-quart stockpot over medium heat, add the onions and garlic with the butter and remaining 2 tablespoons of olive oil. Cook until the onions have slightly caramelized, about 8 minutes. Sprinkle in the crushed red pepper flakes and stir to combine, about 1 minute. Add the oven-roasted tomatoes and stock to the pot and bring to a boil. When soup comes to a full boil, toss in the fresh basil leaves and wilt over medium heat and simmer for about 8 minutes. Working in batches, puree the soup in a blender until smooth, ensuring that the basil leaves are entirely pureed into soup. Adjust seasonings with salt and pepper.
To serve, warm the bread in the oven and the soup in a saucepot over the stove. When bread is heated through, carve a shallow hole in each loaf, and pull a few pieces from the center. Ladle the soup into the bread and serve right away. Garnish with fresh basil leaves and sliced cherry tomatoes, if desired.