Saute onion in butter and add the chopped tomatoes. Add bay leaf, sugar, cloves, salt, pepper and basil. Simmer, stirring occasionally, until tomatoes are thoroughly cooked, about 25 minutes.
Remove bay leaf and cloves and transfer mixture to blender or food processor to puree.
Strain. Add cream and milk and heat through.
Serve topped with toasted buttered croutons. Sprinkle with chopped chives.