Cut the cauliflower into florets. Place the florets in a medium saucepan and add the milk, garlic, bay leaf and a pinch of salt. Bring to a boil over high heat. Reduce heat to a simmer; cover the pot and cook until the florets are tender, about 10-15 minutes.

Using a slotted spoon, transfer the florets and garlic to a food processor (discard the bay leaf). Reserve the cooking liquid. Process the florets until mostly smooth. Add the butter and 1-2 tablespoons of the cooking liquid (more if you want a looser puree). Process until smooth and creamy. Season with salt, pepper and a few drops of lemon juice to taste (you won’t taste the lemon, but it will brighten the flavor). Serve warm. Do Ahead: The puree can be made up to 1 day in advance. Store in a covered container in the refrigerator. Reheat gently before serving (if needed, add a splash or two of water to loosen).