No cream creamy cauliflower soup

I was watching my favorite show, America's Test Kitchen, and they made this.  It's a lot of work, but it is also really interesting how they figured out how to cook the cauliflower in 3 different stages.  I have noticed that as a trend in food these days.  You might get a beet salad with some raw, some pickled, and some roasted.  It really does the vegetable justice I think.  Here is the recipe copied directly from the ATK site, which I followed to the letter, because they do trial after trial and don't present a recipe until it is PERFECT, so why change a thing?!

Ingredients

• 1 head cauliflower (2 pounds)
• 8 tablespoons unsalted butter, cut into 8 pieces
• 1 leek, white and light green parts only, halved lengthwise, sliced thin, and washed thoroughly
• 1 small onion, halved and sliced thin
• Salt and pepper
• 4 1/2 – 5 cups water
• 1/2 teaspoon sherry vinegar
• 3 tablespoons minced fresh chives

Instructions

1. 1. Pull off outer leaves of cauliflower and trim stem. Using paring knife, cut around core to remove; thinly slice core and reserve. Cut heaping 1 cup of 1/2-inch florets from head of cauliflower; set aside. Cut remaining cauliflower crosswise into 1/2-inch thick slices.
   
   2. Melt 3 tablespoons butter in large saucepan over medium-low heat. Add leek, onion, and 1 1/2 teaspoons salt; cook, stirring frequently, until leek and onion are softened but not browned, about 7 minutes.
   
   3. Increase heat to medium-high; add 4 1/2 cups water, sliced core, and half of sliced cauliflower; and bring to simmer. Reduce heat to medium-low and simmer gently for 15 minutes. Add remaining sliced cauliflower, return to simmer, and continue to cook until cauliflower is tender and crumbles easily, 15 to 20 minutes longer.
   
   4. While soup simmers, melt remaining 5 tablespoons butter in 8-inch skillet over medium heat. Add reserved florets and cook, stirring frequently, until florets are golden brown and butter is browned and imparts nutty aroma, 6 to 8 minutes. Remove skillet from heat and use slotted spoon to transfer florets to small bowl. Toss florets with vinegar and season with salt to taste. Pour browned butter in skillet into small bowl and reserve for garnishing.
   
   5. Process soup in blender until smooth, about 45 seconds. Rinse out pan. Return pureed soup to pan and return to simmer over medium heat, adjusting consistency with remaining water as needed (soup should have thick, velvety texture but should be thin enough to settle with flat surface after being stirred) and seasoning with salt to taste. Serve, garnishing individual bowls with browned florets, drizzle of browned butter, and chives and seasoning with pepper to taste.