Remove leaves from rosemary; discard stems. In a stockpot, combine leaves and olive oil. Place the stockpot over medium heat until oil is warm, about 10 minutes. Remove from heat; set aside.Advertisement
When oil is cool, transfer to an airtight container; refrigerate 8 hours or overnight. Strain the infused oil through two layers of cheesecloth; discard leaves. Transfer the oil to small, airtight bottles. Store, refrigerated, up to 2 weeks. Garnish with fresh rosemary sprigs just before the event.