A flavorful cooking oil pressed from hazelnuts, used mainly in European cooking, with Turkey, Italy, Spain, and the United States as the leading producers. It is also called filbert oil. Its nutty, subtly sweet, faintly buttery flavor works well drizzled over salads, pasta, and roasted vegetables, or stirred into baked goods, and it appears in Italian pesto, French pan sauces, and Turkish baklava. Because heat dulls its delicate flavor, it is best used raw or added at the end of cooking rather than as a primary frying oil.