Mashed Potatoes With Rosemary and Leeks with roast

2 whole garlic heads 2 lbs cubed peeled yukon gold potatoes 1 cup chopped onion 2 tablespoons plain fat-free yogurt or 2 tablespoons nonfat sour cream 1[...]

2 whole heads of garlic 2 lbs yukon gold potatoes , cubed, peeled 1 cup onion , chopped 2 tablespoons yogurt , plain, fat-free 1 teaspoon dried rosemary ,[...]