1In 2-quart saucepan, place potatoes; add enough water just to cover potatoes. Heat to boiling; reduce heat. Cover; simmer 20 to 30 minutes or until potatoes are tender. Drain. Shake pan with potatoes over low heat to dry (this will help mashed potatoes be fluffier).
2Mash potatoes in pan until no lumps remain. Add broth in small amounts, mashing after each addition (amount of broth needed to make potatoes smooth and fluffy will vary).
3Add oil, rosemary, salt and cheese. Mash vigorously until potatoes are light and fluffy. Cover; let stand 5 minutes. Sprinkle with additional rosemary and Parmesan cheese if desired.