In a large pot, bring the chicken broth and salt to a boil.
Add the cauliflower and bring back to a boil.
Cover, reduce the heat to low, and steam for 20 minutes, or until the cauliflower is very tender.
Use a slotted spoon to transfer the cauliflower to a food processor fitted with the steel blade. Add 3 tablespoons of the chicken broth from the pot, along with the butter, and process until smooth.
Taste and adjust and seasoning with salt, if necessary, and add pepper to taste.
Add the thyme and process until just combined.
Scrape out the puree into a medium bowl and serve.
This puree can be made up to 2 days ahead of time, refrigerate, and reheat gently in the microwave or on the stovetop.
