In a large pot, combine the tomato paste, tomato juice, cream, stock, 2 tsp salt, the diced tomatoes and the pepper. Bring to a boil over medium-high heat.
Reduce the heat to medium-low and cook, stirring occasionally, until the liquid is reduced by a third.
Purée the soup smooth with an immersion blender, and keep warm over low heat.
Toast the bread slices, and as soon as they come out, brush with olive oil and sprinkle with garlic powder and the remaining salt and pepper.
Add the basil leaves to the soup and let steep over low heat for 5 minutes, then remove the leaves.
Ladle into bowls, garnish with a basil sprig, and serve warm with the garlic toast.