Combine tomatoes and stock in a saucepan.
Simmer 30 minutes. Let cool slightly.
Puree, along with the basil leaves, in small batches, in blender, or better yet, a stick blender.
Return to saucepan and add cream, while stirring, over low heat until cream is incorporated.
Remove from heat and whisk in butter until butter is melted and incorporated.
Taste soup and add salt and pepper to taste.
Ladle into serving bowls and garnish with basil leaves.
Serve with your favorite warm bread.