Place potato pieces in medium saucepan; add water to cover and 1 tsp. salt. Bring to a boil over high heat. Reduce heat to medium low; simmer, uncovered, about 12 to 15 minutes until pieces are tender when pierced with fork. (Do not overcook.) Drain water from pan and set aside.
Place cream, milk, butter and rosemary in small saucepan; heat over medium high heat about 3 minutes or until butter melts and mixture simmers, stirring often.
Mash potatoes with potato masher until smooth. Add roasted garlic and milk mixture; beat with electric mixer until smooth. Beat in remaining 1/2 teaspoon salt and pepper. Serve hot. 4-6 servings
*Roasting Garlic- Cut off top third of the garlic head (not the root end) to expose the cloves; discard the top. Place the head of garlic, trimmed end up, on a 10 inch square of foil. Rub the head generously with olive oil and sprinkle it with salt. Gather the foil ends together and close tightly. Roast in 350 degrees oven 45 minutes or until cloves are golden and the head is soft. Let cool enough to handle,then squeeze gently so roasted cloves slip out of their skins. throw away skins.