Drain the steamed cauliflower thoroughly. Place the cauliflower in a clean kitchen towel or several layers of paper towels and squeeze out as much excess moisture as possible. This step is crucial for creaminess.
Mash by hand with a potato masher until mostly smooth, or process in the food processor until completely smooth and creamy. Scrape down the sides as needed.
If using, stir in the Parmesan cheese. Taste and adjust salt and pepper.
Serve immediately as a side dish.
Notes
Squeezing the moisture out of the cooked cauliflower is the most important step for achieving a non-watery texture.
For a deeper garlic flavor, roast the whole garlic cloves until soft before mashing them with the cauliflower.
If you prefer a thinner consistency, add more warm cream, one tablespoon at a time, until you reach your desired texture.