Cut cauliflower heads into small florets. Set oven to broil. Place half of the florets on a baking sheet and spray or brush with olive oil. Place baking sheet on middle rack of oven and broil until florets are roasted to a medium brown color, about 20 min. Meanwhile, in a large saucepan, bring remaining cauliflower, milk and half and half to a simmer over medium heat. Cover, reduce heat to low and continue to cook until florets are soft, about 20 min. Strain mixture through a colander, reserving both florets and liquid. Place roasted and boiled florets together in a food processor. Add one third of reserved liquid, Capitol Hill Seasoning, salt, white pepper, butter and lemon juice. Puree, adding more reserved liquid as needed to reach desired consistency.