Preheat oven to 300 degrees F. Leaving garlic bulb whole, remove any loose, papery outer layers. Cut bulb in half horizontally to expose individual cloves. Place garlic halves, cut sides down, in a small glass baking dish. Arrange rosemary sprigs around garlic. Sprinkle with pepper; drizzle with oil. Cover with foil. Bake about 40 minutes or until garlic is soft and light brown; cool.
Strain oil mixture through a fine-mesh sieve; discard rosemary sprigs. (Reserve roasted garlic cloves for another use.)
Transfer strained oil to a small airtight storage container. Cover and chill for up to 3 days.