Place the tomatoes cut side up on lined baking trays. Drizzle with olive oil and season.
Roast for 40 minutes, then place into a saucepan with the stock and 2 cups of water. Add the herbs and stir to combine. Simmer for 20 to 25 minutes, then use a slick blender to blend until smooth.
Divide among serving bowls and top with basil leaves (and cream, if you have it).