Season beef with rosemary and, if desired, 1/2 teaspoon salt and 1/4 teaspoon ground black pepper.
In 12-inch nonstick skillet, heat 1 tablespoon Olive Oil over high heat, and brown beef. In small roasting pan, arrange beef and roast 15 minutes or until desired doneness. Let stand 10 minutes before slicing.
Meanwhile, in same skillet, heat remaining 1 tablespoon Olive Oil over medium-high heat and cook mushrooms and shallot, stirring frequently, 4 minutes or until golden.
Add garlic and cook, stirring frequently, 1 minute. Stir in wine and bring to a boil over high heat. Reduce heat to medium and simmer 2 minutes. Stir in half and half; heat through. Season, if desired, with salt and ground black pepper. Serve sauce over sliced beef.