For Dev, who asked...
2C mashed potatoes
5-1/2C coarsely chopped cauliflower, about 1 small head
6 garlic cloves
1 bay leaf
Heat potatoes; keep warm. Cook cauliflower in boiling water 7 minutes or until tender; drain.
Place milk, garlic and bay leaf in small pot; bring to simmer. Cover and cook over low heat 10 minutes. Discard bay leaf. Place cauliflower, milk (with garlic), butter and salt in processor. Puree until smooth, scraping down sides. Combine potatoes with cauliflower mixture in large bowl until blended.
Note: I used the refrigerator mashed potatoes from Simply Potatoes. They are really quite good. Homemade would work, too, of course!