In a food processor or blender combine 1/2 cup olive oil, basil, olives, cheese, garlic, and salt. Cover and process until until nearly smooth, stopping and scraping sides as necessary and adding additional oil as needed to reach desired consistency. Season to taste with pepper.
If youre not serving the pesto immediately, divide it into 1/4-cup portions. Place each portion in a small airtight container and refrigerate for 1 to 2 days or freeze for up to 3 months. Makes 1-3/4 cups.