Prepare the ingredients. Cut the cauliflower into small pieces and place in a saucepan with the garlic clove and thyme sprig. Add enough water to cover.

Cook the cauliflower until tender. Drain, reserving the cooking water. Remove the thyme sprig (it’s fine if some leaves remain). Process the cauliflower and garlic in a food processor until smooth.

If needed, add the reserved cooking water one tablespoon at a time, being careful not to make it too watery. Add the butter and Parmesan cheese, and process until well combined.

Return the purée to the saucepan and heat over medium, stirring constantly, until the butter and cheese are melted. Stir in the heavy cream and season with salt, white pepper, and nutmeg to taste. Serve as a side dish with any main course.