1. Into large bowl, measure all ingredients except prunes. With mixer at low speed, beat ingredients until blended, occasionally scraping bowl with rubber spatula. Stir in prunes.
2. Preheat oven to 350°F. Drop mixture by heaping tablespoonfuls, about 2 inches apart, onto ungreased large cookie sheet. Bake cookies 15 minutes or until golden. With pancake turner, carefully remove cookies to wire racks to cool. Repeat with remaining dough. Store cookies in tightly covered container.