TOSS cauliflower with oil, salt and pepper; spread onto bottom of half-sheet pan. Bake in 350ºF convection oven 10 to 15 min. or until lightly browned.
MELT butter in large saute pan. Add celery, leeks, parsnips and garlic; saute until tender. Add broccoli and 2 cups broth (or 1 cup broth for trial recipe); cover. Simmer until vegetables are softened. Add to blender; blend until pureed, adding additional broth as needed.
POUR 2 cups of the remaining broth (or 1 cup of the remaining broth for trial recipe) into large sauce pot. Add VELVEETA and cream cheese; cook on low heat until completely melted, stirring frequently. (Be careful to not let sauce burn.) Whisk in pureed vegetables until blended. Gradually stir in remaining broth until soup is of desired consistency.
FOR each serving: Ladle 1 cup soup into bowl; top with 1 piece of roasted cauliflower.