This creamy cauliflower puree is a satisfying low-carb swap for high-carb mashed potatoes. The leeks, garlic and herbs give it more flavor and texture. Make them up to 3 days ahead for enjoying during the busy week or for your holiday table. For dairy-free, use a plant-based butter, for vegan, vegetable broth.
Trim the head of cauliflower into florets. Cut all the way around the center core with a sharp paring knife. Break florets off by hand. If needed, cut them into smaller florets that will fit in your steamer.
Add a few inches of water to a large 5-6 quart pot. Place steamer rack inside the pot. Water should come to the bottom of the rack. Turn heat to high and cover pot with a tight fitting lid. When water is steaming, add the cauliflower, cover and turn to medium-low. Steam florets until very tender when pierced with the tip of a sharp paring knife, 12-15 minutes.
While cauliflower is steaming, cook the leeks. Slice the leek in half and run under cold water to dislodge any sandy grit. Dry leek and chop crosswise into thin pieces. Heat oil in a medium fry pan over medium low heat adn cook leek until soft and tender, 2-3 minutes then add the garlic and cook another 30 seconds.
Add cauliflower, leeks and garlic to the work bowl of a food processor and puree, adding the butter, thyme, salt and pepper. Add the broth at the end to adjust creaminess. Serve hot or cool, cover and refrigerate up to 3 days, then reheat to serve.