- 3 1/4 pounds russet potatoes, peeled, cut into 1-inch pieces
- 4 large garlic cloves, peeled
- 1/2 cup (1 stick) butter
- 3 1/2 ounces thinly sliced prosciutto, finely chopped
- 3/4 teaspoon minced fresh rosemary
- 3/4 cup (or more) whole milk
- 1 cup freshly grated Parmesan cheese (about 3 ounces)
- Additional fresh rosemary
Cook potatoes and garlic in large pot of boiling salted water until potatoes are very tender, about 15 minutes. Drain; return potatoes and garlic to same pot.
Meanwhile, melt 1/2 cup butter in heavy small saucepan over medium heat. Add chopped prosciutto and 3/4 teaspoon minced rosemary and sauté until fragrant, about 2 minutes.
Add prosciutto mixture and 3/4 cup milk to potatoes and garlic. Mash well, adding more milk by tablespoonfuls if potatoes are dry. Mix in 3/4 cup cheese. Season with salt and pepper. (Can be prepared 6 hours ahead. Cover and chill. Stir over low heat to rewarm, adding more milk by tablespoonfuls, if desired.) Transfer potatoes to bowl. Sprinkle with remaining 1/4 cup cheese; garnish with fresh rosemary and serve.