I have a recipe like that - here is what I do:
Equal amounts of tomato sauce and half and half (or a combo of heavy cream and half and half to equal the amount of tomato sauce).
Heat this gently with some sprigs of fresh thyme. Once heated (about 15 or so minutes) remove sprigs of thyme and add fresh basil chiffonade.
This was always a winner at the restaurant - it's amazing how simple it is. Pureed tomatoes would work too, I feel sure! Salt and pepper as necessary, of course.